Property Development Feasibility Spreadsheets: The Australian Developer's Complete Guide

A Melbourne developer we spoke to recently discovered a $247,000 error in their townhouse feasibility—buried in cell D47 of a spreadsheet they’d been using for three months. The formula calculating GST credits had a hardcoded value from a previous project. By the time their accountant caught it during due diligence, they’d already committed to the purchase with a non-refundable deposit at risk.

This isn’t an isolated incident. Industry research suggests that approximately 73% of property developers begin their feasibility analysis using Excel or Google Sheets, and roughly 40% of those models contain material errors that affect investment decisions. The challenge isn’t that spreadsheets are inherently flawed—it’s that Australian property development has specific regulatory, taxation, and compliance requirements that generic templates consistently miss.

This guide covers what Australian developers may need to know about building and using feasibility spreadsheets effectively, including the state-specific requirements, GST considerations, and cost structures that international templates typically overlook. Whether you’re building your first model or refining an existing approach, understanding these fundamentals could help you avoid expensive mistakes and make more informed investment decisions.

Why Australian Developers Start With Spreadsheets (And That’s Often Appropriate)

For developers evaluating their first acquisition or analysing a straightforward duplex development, spreadsheets typically provide a reasonable starting point. The initial financial outlay is minimal, the interface is familiar, and the flexibility allows you to structure calculations exactly as you prefer. Many experienced developers maintain that building a feasibility model from scratch in Excel helps you understand the mechanics of development returns more thoroughly than using pre-built software.

The spreadsheet approach generally works well when your development scope is relatively contained—perhaps a 2-4 unit project on a single title with straightforward planning approval requirements and conventional bank financing. In these scenarios, the time investment to build a robust model may be justified, and the complexity typically remains manageable for one person to maintain and update.

However, complexity in property development tends to accelerate faster than most developers initially anticipate. What begins as a simple feasibility calculation for a duplex can evolve into a multi-scenario analysis comparing different unit mixes, staged construction approaches, various funding structures, and sensitivity testing around construction cost escalation. At this point, spreadsheets can become unwieldy—particularly when you need to share models with partners, present to financiers, or compare multiple sites simultaneously.

While Feasly is designed for developers who’ve outgrown basic spreadsheet approaches, understanding spreadsheet fundamentals helps you recognise what questions to ask and which assumptions matter most in your feasibility analysis. The goal isn’t to abandon spreadsheets entirely, but to understand their appropriate application and limitations in the Australian development context.

The 8 Critical Components Every Australian Feasibility Model Must Include

1. Acquisition Costs With State-Specific Calculations

The purchase price is typically just the beginning of your acquisition costs. Australian developers face a complex web of state-based charges that can add 5-8% to the headline purchase figure—and getting these calculations wrong could mean underestimating your total capital requirement by $100,000 or more on a $2 million site.

Stamp duty variations by state create the most significant cost differences. As of 2025, transfer duty rates on property purchases generally range from 3.75% in Queensland to 5.5% in New South Wales and Victoria, with progressive rate structures that increase as purchase prices rise. NSW Revenue and State Revenue Office Victoria provide current rate schedules, though these may be subject to periodic adjustment.

Foreign buyer surcharges represent an additional cost layer that many feasibility templates overlook. Foreign persons typically face additional duty charges of 7-8% in most states, plus annual surcharges in some jurisdictions. If you’re structuring a purchase through a trust or company with foreign beneficiaries, even partial foreign ownership may trigger these additional charges. FIRB (Foreign Investment Review Board) provides guidance on foreign investment regulations, though recent policy changes mean developers should verify current rules before finalising purchase structures.

GST treatment on land purchases requires careful consideration, as it affects both acquisition costs and your eligibility for the GST margin scheme on eventual sales. If you’re purchasing from a GST-registered entity selling as part of their enterprise (such as buying from another developer), you may face a going concern exemption or margin scheme application on the purchase side. The Australian Taxation Office offers detailed guidance on property GST matters, though complex scenarios typically warrant professional advice.

Additional acquisition costs may include:

• Legal and conveyancing fees: typically $3,000-$8,000 depending on transaction complexity
• Building and pest inspections: $500-$1,500 for standard residential properties
• Town planning reports: $2,000-$5,000 for preliminary planning advice
• Contamination assessments: $3,000-$15,000 if Phase 1 or 2 Environmental Site Assessments are required
• Survey costs: $2,000-$5,000 for identification or feature surveys
• Finance establishment fees: 0.5-1.5% of loan value

2. GST & The Margin Scheme—Australia’s Most Misunderstood Tax Treatment

The GST margin scheme represents one of the most significant opportunities for cost optimisation in Australian property development, yet it remains poorly understood by many developers and frequently miscalculated in generic feasibility templates. Understanding how the margin scheme works—and when you’re eligible to use it—could potentially save $50,000-$150,000 or more on a typical residential development project.

Under the standard GST treatment, developers pay GST (one-eleventh of the sale price) to the ATO on the full sale price of new residential premises. However, if certain conditions are met, the margin scheme allows you to pay GST only on your profit margin—calculated as the difference between your sale price and your acquisition cost. For developments on land purchased at market rates, this typically results in substantially lower GST payments to the ATO.

Eligibility for the margin scheme generally requires that the property was acquired under the margin scheme or no GST was payable on acquisition (such as purchasing from a non-GST registered vendor). You cannot use the margin scheme if you purchased the property with full GST credits claimed—a common situation when buying from other developers or GST-registered entities conducting an enterprise.

The calculation methodology can become complex when improvements exist on the acquired site. If you’re purchasing a property with an existing dwelling that you intend to demolish and redevelop, the margin scheme calculation may need to account for the GST-inclusive value of those improvements. The ATO’s detailed guidance on the margin scheme provides worked examples, though complex scenarios typically warrant engagement with a property tax specialist.

Consider a simplified example: If you purchase a development site for $1,500,000 (GST-free from a non-registered vendor) and create 8 townhouses that sell for a total of $4,800,000:

Standard GST treatment:

• GST payable: $436,364 (one-eleventh of $4,800,000)

Margin scheme treatment:

• Margin: $4,800,000 - $1,500,000 = $3,300,000
• GST payable: $300,000 (one-eleventh of the margin)
• Saving: $136,364

This saving flows directly to your development margin and could significantly affect project viability. However, once you elect to use the margin scheme, you’re typically required to hold to that election for the entire development. Mixing margin scheme and standard GST treatment within a single project is generally not permitted.

Feasly’s GST system handles both standard and margin scheme methodologies, allowing you to model different scenarios and understand the impact on your net cash position. The software prompts you to confirm margin scheme eligibility based on your acquisition structure, reducing the risk of miscalculating this critical component.

3. Construction Costs With Australian Market Benchmarks

Accurately estimating construction costs represents perhaps the most challenging aspect of feasibility modelling, as costs can vary dramatically based on site conditions, design complexity, specification level, and current market capacity. Generic construction cost estimates from international templates rarely reflect Australian building standards, labour rates, or material costs—making them essentially useless for decision-making.

Australian construction costs typically range from $2,200-$2,800 per square metre for standard townhouse construction in metropolitan markets, rising to $2,800-$3,500+ per square metre for apartments requiring basement parking and lift access. These figures generally represent a mid-specification finish with standard inclusions. Premium finishes, complex architectural designs, or difficult site conditions could push costs to $3,500-$4,500 per square metre or beyond.

Rawlinsons Australian Construction Handbook and Rider Levett Bucknall publish regular cost indices that many quantity surveyors reference, though these represent broad market averages. Your actual costs may vary significantly based on:

• Site conditions: Rock excavation, contaminated soil remediation, services relocation, or restricted site access can add 10-30% to baseline costs
• Design complexity: Unusual building forms, extensive glazing, or high-end finishes increase costs substantially
• Market capacity: During construction booms, labour shortages and material constraints typically drive prices 15-25% above normal levels
• Location factors: Remote or regional areas face higher transport costs and potentially limited trade availability
• Project scale: Smaller projects (under 10 units) typically face higher per-unit costs due to reduced economies of scale

Most experienced developers include construction contingencies of 10-15% to account for variations, design changes, and unforeseen conditions discovered during construction. Inadequate contingency provisioning represents a common reason why developments exceed feasibility budgets, as even well-documented projects typically encounter some scope changes or site surprises.

4. Professional Fees—What Consultants Actually Charge

Professional fees typically consume 8-15% of your total development budget, yet many feasibility models substantially underestimate this cost category by missing consultants entirely or using outdated fee structures. Understanding which professionals you’ll likely need to engage—and what they typically charge—is essential for accurate feasibility analysis.

Architect fees generally range from 4-7% of the construction value for full architectural services from concept design through to practical completion. For a $2.5 million construction project, this typically means $100,000-$175,000 in architectural fees. Some architects offer staged fee structures where you pay lower rates for concept design and development application documentation, with the option to novate the architect to your builder for construction phase services. Alternatively, employing a “design and construct” builder may reduce direct architectural costs, as the builder engages the architect, though this typically results in less design control.

Engineering consultants may include structural engineers, civil engineers, hydraulic consultants, geotechnical engineers, and others depending on project complexity. Collectively, engineering fees typically represent 2-4% of construction value, or $50,000-$100,000 on a $2.5 million project. Geotechnical investigations alone can cost $5,000-$20,000 depending on the number of boreholes required and subsurface conditions encountered.

Town planning consultants typically charge $5,000-$25,000 to manage development application preparation and submission, with fees varying based on project complexity and the level of council engagement required. Projects requiring public consultation, design review panels, or appeals to planning tribunals will incur substantially higher planning costs—potentially $50,000-$100,000+ if legal representation becomes necessary.

Quantity surveyors may charge $3,000-$12,000 for cost planning and tender documentation, depending on project scale. For developers claiming tax depreciation, a separate depreciation schedule typically costs $500-$1,200 per property and should be included in feasibility budgets.

Additional professional costs may include:

• Building surveyors: $3,000-$15,000 for private building certification
• Traffic consultants: $5,000-$20,000 if traffic impact assessments are required
• Acoustic consultants: $3,000-$10,000 for noise impact assessments in mixed-use or high-density areas
• Landscape architects: $5,000-$25,000 depending on landscape complexity requirements
• Arborists: $2,000-$8,000 if tree protection or removal is required
• Environmental consultants: $3,000-$30,000+ depending on contamination complexity

Marketing and sales costs typically represent 2-3% of gross sales revenue for residential projects. For an $8 million development, this suggests $160,000-$240,000 in combined marketing and sales agent commissions. Many developers underestimate marketing costs by focusing only on agent commissions (typically 2-2.5%) while neglecting display suite costs, professional marketing materials, digital advertising, and styling expenses.

5. Council Contributions & Infrastructure Charges

Development contributions represent one of the least transparent cost categories in Australian property development, varying dramatically by local government area and frequently catching developers by surprise. These charges—which can range from $5,000 to $40,000+ per dwelling in high-growth areas—typically fund local infrastructure like roads, parks, community facilities, and drainage systems.

New South Wales operates under Section 7.11 and Section 7.12 contribution frameworks, with many councils publishing detailed Development Contributions Plans that specify per-dwelling or per-square-metre charges. The NSW Department of Planning and Environment provides guidance on contribution frameworks, though developers need to review specific council contribution plans to determine actual charges. Some Sydney councils charge $30,000-$40,000+ per dwelling for residential development in growth areas, representing a material feasibility impact that generic templates typically ignore.

Victoria uses Development Contribution Plans (DCPs) and Infrastructure Contribution Plans (ICPs) in growth areas, with charges varying substantially by location. The Victorian Planning Authority oversees contribution frameworks in designated growth areas, though specific charges depend on which precinct structure plan applies to your site.

Queensland employs infrastructure charges calculated based on adopted charges schedules that vary by council and development type. The State Development Assessment Provisions provide frameworks, though individual council schedules determine actual charges. Some councils offer infrastructure charges as a fixed amount per dwelling, while others use more complex calculations based on development impact assessments.

Western Australia, South Australia, Tasmania, Northern Territory, and ACT each maintain different contribution frameworks, with varying levels of prescription and transparency. Developers should consult individual council planning schemes and contribution policies early in the acquisition process, as these charges may significantly affect development viability.

Beyond infrastructure contributions, councils typically charge various statutory fees including:

• Development application fees: typically $2,000-$15,000 depending on development value
• Long service leave levy: 0.35% of construction value in NSW, varying in other states
• Building inspection fees if using council certification
• Section 68 approval fees for works affecting public infrastructure

6. BASIX & Sustainability Compliance Costs

State-based sustainability requirements add tangible costs to development projects, yet many feasibility templates either ignore these requirements entirely or use outdated cost assumptions. Understanding current sustainability standards—and budgeting appropriately for compliance—helps prevent unexpected cost surprises during design development.

New South Wales BASIX (Building Sustainability Index) requirements apply to most new residential development, mandating minimum performance standards for water, thermal comfort, and energy use. Research from the NSW Department of Planning, Housing and Infrastructure suggests BASIX compliance typically costs approximately $7,152 per dwelling in additional construction costs, though this varies based on building type and the level of performance required. These costs may include enhanced insulation, water-efficient fixtures, solar panels or solar hot water systems, and improved window performance.

Victoria’s 6-star NatHERS requirement for new homes represents a similar compliance burden, typically costing $5,000-$12,000 per dwelling depending on design approach. Developers can achieve higher star ratings through improved building fabric (insulation, windows, building sealing) or by incorporating fixed appliances like heating and cooling systems into the NatHERS assessment. Design choices significantly affect compliance costs—passive solar design principles may achieve required ratings more cost-effectively than relying on mechanical systems.

Other states maintain varying sustainability requirements:

• Queensland: 6-star energy rating under NatHERS, plus water efficiency requirements
• South Australia: 6-star NatHERS energy rating
• Western Australia: Generally requires compliance with NatHERS or equivalent
• Tasmania: Energy efficiency requirements under the Building Code of Australia
• ACT: 6-star NatHERS energy rating minimum
• Northern Territory: Climate zone-appropriate energy efficiency standards

For apartment developments, common area sustainability measures may include rainwater harvesting systems, solar power for common areas, electric vehicle charging infrastructure, bicycle storage, and enhanced waste management facilities. Green Star ratings or other voluntary certification schemes carry additional consultant fees ($15,000-$50,000+) and incremental construction costs that need careful evaluation against marketing benefits.

7. Development Finance Structure & Cash Flow Complexity

Finance modelling separates basic feasibility spreadsheets from professional-grade development analysis. While calculating total interest costs using a simple average loan balance might suffice for back-of-envelope calculations, accurate feasibility modelling requires monthly cash flow projections that account for draw-down timing, interest capitalisation, and the interaction between construction progress and funding requirements.

Most development finance structures involve multiple funding tranches:

• Land acquisition loan: Typically 60-70% of land value at current senior debt rates (approximately 6.5-8.5% as of late 2025)
• Construction facility: Additional funding for construction costs, usually drawn progressively as works proceed
• Mezzanine finance (if required): Subordinated debt filling the gap between senior debt and equity, typically 12-18% interest rates
• Equity contribution: Developer equity plus any joint venture partner capital

Senior lenders typically require presales of 60-80% for apartment projects before releasing construction funding, with exact requirements varying by lender and market conditions. For townhouse projects, some lenders offer construction finance with lower or no presales requirements, though this typically results in higher interest rates or lower loan-to-value ratios.

Interest capitalisation means developers rarely pay interest monthly during construction—instead, interest charges are added to the loan balance and repaid at settlement. This creates a compounding effect where you’re paying interest on previously capitalised interest. For a $3 million construction facility drawn over 12 months at 7.5% interest, total interest costs typically exceed $140,000 by practical completion, with approximately $8,000-$10,000 of that representing interest charged on previously capitalised interest.

S-curve cash flow patterns reflect how construction spending typically proceeds—slowly in early months during site establishment and substructure works, peaking during frame and fit-out stages, then declining as projects approach completion. This pattern significantly affects interest calculations, as average loan balances are typically 50-60% of peak debt rather than a simple average of zero and peak debt.

Feasly handles multi-tranche funding structures and monthly cash flow projections without requiring complex formulas that can break when copied or modified. The platform helps you apply different rates to different funding tranches, and shows you cumulative cash requirements throughout the development timeline. This level of detail becomes critical when presenting to financiers or when modelling the impact of construction delays on total finance costs.

8. Sales Revenue Modelling & Absorption Rate Realism

Revenue projections in feasibility models require balancing optimism about market values with realistic assumptions about sales timing, pricing pressure, and the gap between contract prices and settlement receipts. Many failed developments weren’t fundamentally unsound—they simply ran out of cash because sales timing assumptions proved overly optimistic and interim financing became unsustainable.

Presales vs final settlements create timing gaps that must be modelled in cash flow projections. Buyers typically pay 10% deposit on contract, with the balance due at settlement. For off-the-plan sales, contracts might be exchanged 12-18 months before completion, meaning you receive deposit funds early but must finance the project until settlements occur. Some lenders will lend against presale contracts, recognising a percentage (typically 70-80%) of presale values when assessing loan serviceability and gearing.

Marketing period assumptions should reflect realistic absorption rates for your location and product type. Townhouse projects in established suburbs might presell 50-70% during construction, with remaining stock selling over 3-6 months post-completion. Apartment projects often require longer marketing campaigns—potentially 12-18 months to achieve full sales in competitive markets. Assuming you’ll sell everything within 3 months of completion rarely reflects market reality and may leave you unable to repay construction debt when due.

Agent commission structures typically involve a base commission (2-2.5% of sale prices) plus potentially higher rates for difficult or final stock. Some developers negotiate tiered commissions—lower rates for initial presales when stock is easier to move, higher rates for final units that may require price reductions or extended marketing. Budget for the higher commission rate on at least 20-30% of stock unless you have evidence supporting full sales at base commission rates.

Settlement risk provisioning recognises that 5-10% of off-the-plan contracts may fall over before settlement, particularly if the property market declines or buyers’ financial circumstances change. While you typically retain the 10% deposit when buyers default, finding replacement buyers takes time and may require price reductions. Conservative feasibility models build in some settlement failure assumption rather than assuming 100% of contracted sales will settle at full price.

Model different sales scenarios in Feasly—fast absorption with strong pricing, moderate absorption at target prices, or extended marketing with price reductions. Being able to test multiple scenarios quickly helps you understand how sensitive your development margin is to sales timing and pricing variation. Projects showing positive returns only under optimistic sales assumptions may require redesign, reduced site acquisition costs, or additional equity to provide adequate risk buffer.

Where Spreadsheets Actually Start to Break Down

The progression from simple feasibility spreadsheet to unmaintainable complexity typically follows a predictable pattern. What begins as a straightforward model evolves through successive modifications—adding scenarios, incorporating partner feedback, adjusting for new council requirements, modelling different unit mixes—until the original structure becomes difficult to verify and errors become increasingly likely.

Formula errors in critical cells represent the most dangerous spreadsheet risk because they’re often invisible. A colleague modifies a formula in one cell, intending to update an assumption, and accidentally deletes or changes a cell reference. The spreadsheet continues calculating, producing numbers that appear plausible, but the underlying logic is now flawed. These errors typically go undetected until someone manually checks calculations or an accountant questions assumptions during due diligence.

Version control becomes problematic when multiple stakeholders need access to feasibility models. Email attachments accumulate: Feasibility_v2.xlsx, Feasibility_v3_revised.xlsx, Feasibility_FINAL.xlsx, Feasibility_FINAL_v2.xlsx, Feasibility_FINAL_ACTUAL.xlsx. Which version contains the current assumptions? Did your quantity surveyor’s updated cost estimate get incorporated into the version your joint venture partner is reviewing? Has anyone checked whether the file your financier received matches your current analysis?

Comparing multiple sites or scenarios becomes increasingly difficult with spreadsheet approaches. You might duplicate the entire workbook for each site you’re evaluating, meaning any methodology improvements or assumption changes must be manually replicated across multiple files. Alternatively, you could build comparison logic into a single spreadsheet, but this typically creates enormous workbooks with multiple tabs and complex cell references that few people can confidently navigate.

GST calculations frequently contain errors in custom spreadsheets, particularly when developers attempt to model both margin scheme and standard GST scenarios or when dealing with mixed-use developments that combine residential (GST-applicable) and commercial (potentially GST-free if going concern) components. The interaction between input tax credits, output tax liabilities, and settlement timing creates complexity that simple formulas often handle incorrectly.

No audit trail exists when critical assumptions change. Who changed the construction cost from $2,800 to $2,650 per square metre? When did that change occur? What was the justification? Spreadsheets don’t maintain change logs, making it difficult to understand how feasibility has evolved or to identify when errors were introduced. This becomes particularly problematic when disputes arise with partners or when investors question why feasibility outcomes differ from original projections.

Team collaboration limitations mean that typically only one person understands the spreadsheet’s formula logic and structure. If that person leaves the business or is unavailable when urgent decisions are required, other team members struggle to use or modify the model confidently. This creates key person risk that professional businesses generally seek to avoid.

This is fundamentally why Feasly was built for Australian developers. The platform is browser-based, meaning your entire team sees the same version without email attachments or synchronisation issues. You can duplicate feasibility analyses in seconds, making site comparison straightforward.

State-by-State Development Requirements: What Your Feasibility Must Include

Australian property development operates under state-based planning and taxation frameworks, creating substantial variation in costs, approval processes, and timeline expectations. Understanding these differences becomes critical when comparing potential sites across state borders or when using templates developed for different jurisdictions.

This table provides general guidance only, as specific requirements may vary by location within each state, property type, and development scale. Developers should verify current rates and requirements with relevant authorities before making investment decisions.

Links to state planning authorities:

• NSW Planning Portal
• Victoria Planning
• Queensland Development
• WA Planning
• SA Planning Portal
• TAS Planning
• ACT Planning
• NT Planning

Real Case Study: 6-Unit Townhouse Development in Melbourne

To illustrate how these feasibility components work together in practice, consider a hypothetical 6-unit townhouse development in Melbourne’s middle ring suburbs. This example uses realistic numbers based on current market conditions, though actual feasibility would vary based on specific location, site conditions, and design approach.

Site Acquisition

• Land purchase price: $1,650,000
• Victorian stamp duty (5.5%): $90,750
• Legal and conveyancing: $4,500
• Due diligence costs (building inspection, town planning report, preliminary soil test): $6,200
• Total acquisition cost: $1,751,450

Development Costs

• Demolition of existing dwelling: $25,000
• Site costs (services, retaining, erosion control): $95,000
• Construction costs (6 x 180m² townhouses @ $2,650/m²): $2,862,000
• Contingency provision (12%): $343,440
• Total construction costs: $3,325,440

Professional Fees

• Architect (5.5% of construction): $157,420
• Structural & civil engineering: $62,000
• Geotechnical investigation: $8,500
• Town planner: $14,500
• Building surveyor: $9,200
• Quantity surveyor: $7,500
• Landscape architect: $12,000
• Total professional fees: $271,120

Authority & Sustainability Costs

• Development application fees: $8,400
• Building permit fees: $6,200
• 6-star NatHERS compliance (6 units @ $8,500): $51,000
• Infrastructure contributions (council-specific): $78,000
• Long service leave levy (0.35% of construction): $10,025
• Total authority costs: $153,625

Finance Costs

• Land holding costs (12 months @ 7.5% on $1,400,000 loan): $105,000
• Construction interest (capitalised, 18 months average exposure $2,100,000 @ 7.8%): $245,700
• Bank establishment fees (1.2% of $3,500,000 total facility): $42,000
• Legal fees for finance: $4,800
• Total finance costs: $397,500

Marketing & Sales

• Marketing campaign and display costs: $95,000
• Sales agent commission (2.2% of GRV): $114,840
• Legal fees for contracts of sale: $18,000
• Total sales costs: $227,840

Total Development Costs: $6,127,975

Revenue Projection

• 6 townhouses sold @ average $870,000 each: $5,220,000
• Less GST (assuming margin scheme eligible, 1/11 of margin): $315,684
• Net revenue: $4,904,316

Development Outcome

• Gross deficit: -$1,223,659
• This project is not feasible at these assumptions

This illustrative example demonstrates why thorough feasibility analysis matters. At first glance, selling 6 townhouses for $870,000 each against a land purchase of $1,650,000 might seem viable. However, when all development costs are properly accounted for—including professional fees, authority charges, finance costs, and realistic construction contingencies—the project shows a substantial deficit rather than profit.

This scenario might become feasible through:

• Increased sale prices to $920,000+ per townhouse
• Reduced land acquisition cost to $1,350,000 or below
• Value engineering to reduce construction costs by 8-10%
• Faster project delivery reducing finance costs
• Some combination of the above adjustments

This entire feasibility analysis would typically require 2-3 hours to build properly in Excel, incorporating all state-specific costs, GST calculations, and cash flow timing. In Feasly, you could model it in 15-20 minutes, then instantly create variations—testing 5 units instead of 6, different finishes specifications, alternative sales pricing, or reduced acquisition cost scenarios. The ability to rapidly test multiple scenarios helps you understand which variables most significantly affect feasibility and where you might focus negotiation efforts.

When to Graduate From Spreadsheets to Professional Feasibility Tools

Not every developer requires professional feasibility software, and being honest about when spreadsheets remain appropriate helps you make informed decisions about tool investment. The sophistication of your analysis should match the complexity of your developments and the pace of your business.

Spreadsheets may continue to serve you adequately if:

• You’re undertaking a single, simple development project (2-4 units, single title, straightforward planning approval)
• Time sensitivity isn’t critical—you can afford to spend several days building and validating models
• You enjoy building complex financial models and have strong Excel skills
• You’re undertaking a one-off development project rather than building an ongoing development business
• Only one person needs to understand and use the feasibility model
• You’re not comparing multiple sites simultaneously or running extensive scenario analyses

Consider professional feasibility tools when:

• You’re evaluating 3+ potential acquisition sites simultaneously and need rapid comparison capability
• Your projects involve complexity: staged developments, multiple funding tranches, joint venture structures, or mixed-use components
• Multiple team members need to access and understand feasibility analysis—partners, investors, project managers, or external consultants
• You’re undertaking 3+ development projects per year and want consistent methodology across all feasibilities
• Projects exceed $2-3 million in total development cost, where modelling errors could cost tens of thousands
• You need to present feasibility analysis to financiers or investors frequently and require professional documentation
• Cash flow timing is critical—you need accurate monthly projections for construction finance management
• You’re comparing scenarios extensively—testing different unit mixes, staged vs single-phase development, various funding structures

The investment in professional feasibility software typically represents 0.05-0.15% of total project costs—a modest amount relative to the capital at risk and the potential cost of modelling errors or poor decision-making. For developers undertaking $5 million+ projects or running an active development business, professional tools generally pay for themselves through time savings, reduced errors, and better informed decision-making.

However, the tool matters less than understanding the fundamentals. Developers who’ve built detailed spreadsheet models typically understand feasibility mechanics more thoroughly than those who’ve only used software with pre-configured templates. The ideal progression might be: build several detailed models in Excel to understand the mechanics, then graduate to professional software when complexity or volume justifies the investment.

Australian-Specific Feasibility Checklist

Use this checklist to verify your feasibility model includes all critical components for Australian property development. Missing any of these items may result in underestimated costs or inaccurate profitability projections.

Acquisition Costs

• Purchase price agreed or realistic market estimate
• Correct state stamp duty calculation including applicable concessions
• Foreign buyer surcharge if applicable (7-12% depending on state)
• GST treatment on land purchase verified
• Legal and conveyancing fees ($3,000-$8,000)
• Building and pest inspections ($500-$1,500)
• Survey costs ($2,000-$5,000)
• Soil testing or contamination assessment ($3,000-$15,000)
• Town planning preliminary advice ($2,000-$5,000)

Construction Costs

• Construction costs using Australian benchmarks ($2,200-$3,500+/m²)
• Current cost escalation factors applied (5-8% annual increase typical in recent years)
• Site-specific cost adjustments (rock, contamination, access constraints)
• Appropriate contingency provision (10-15% typical)
• Demolition costs if existing structures present
• Site costs (retaining, services relocation, erosion control)
• Utility connection fees (water, sewer, power, gas)

Professional Fees

• Architect fees (4-7% of construction value)
• Structural and civil engineering
• Geotechnical investigation
• Town planning consultant
• Building surveyor/certifier
• Quantity surveyor
• Landscape architect (if required)
• Other specialist consultants (traffic, acoustic, arborist, etc.)

Authority Costs & Compliance

• Development application fees
• Building permit fees
• Section 7.11/7.12 contributions (NSW) or state equivalent
• Council infrastructure charges specific to your LGA
• BASIX costs (NSW) or 6-star NatHERS (other states)
• Long service leave levy (state-specific)
• Occupation certificate fees
• FIRB application if foreign investment involved

Finance Costs

• Realistic interest rates (6-8.5% senior debt, 12-18% mezzanine)
• Finance establishment fees (0.5-1.5% of facility)
• Legal fees for finance documentation
• Interest calculated on monthly cash flow basis (not simple average)
• Presales requirements by lender factored into cash flow
• Exit strategy and refinance costs if applicable

GST Treatment

• Margin scheme eligibility determined based on acquisition structure
• GST calculation uses correct methodology (1/11 of margin vs 1/11 of full sale price)
• Going concern exemptions considered for commercial components
• Input tax credits timing aligned with cash flow

Sales & Marketing

• Realistic sales pricing based on comparable recent sales
• Marketing campaign budget (typically $50,000-$150,000 for multi-unit projects)
• Sales agent commission (2-2.5% base rate, potentially higher for final stock)
• Realistic absorption rate (avoid assuming 100% sales in 3 months)
• Legal fees for contracts of sale
• Settlement risk provision (5-10% contract failure rate)
• Timing between presales, practical completion, and final settlements

Project Timeline

• Development application timeline (3-6 months typical, longer for complex)
• Construction permit timeline (1-2 months typically)
• Construction duration realistic for project scale (12-18 months for townhouses, 18-30 months for apartments)
• Marketing and sales period (typically 6-12 months for presales, 3-6 months post-completion)
• Settlement period after practical completion (1-3 months typically)

Risk Provisions

• Construction contingency (10-15%)
• Cost escalation for projects starting 12+ months from feasibility date
• Settlement failure provision
• Extended holding costs if sales slower than projected
• Interest rate sensitivity testing (model impact of 1-2% rate increases)

Taking Your Feasibility Analysis to the Next Level

Understanding these fundamentals positions you to make better informed development decisions, whether you’re working in spreadsheets or considering professional software tools. The Australian property development market has specific regulatory, taxation, and cost structures that generic templates typically miss—incorporating these elements into your analysis creates more reliable feasibility projections.

Whether you continue using spreadsheets or explore professional software, the key is ensuring your feasibility analysis addresses the specific requirements of Australian property development. The time invested in building robust feasibility models—including all the regulatory costs, state-specific charges, and realistic timing assumptions—generally pays dividends through better acquisition decisions, more accurate budgeting, and earlier identification of projects that may not deliver adequate returns.

Start by verifying your current approach against the checklist above. Identify which components you might be underestimating or missing entirely. Update your assumptions using current market data. And recognise that feasibility modelling is a skill that improves with practice - each project teaches you which assumptions matter most and where your previous estimates proved optimistic or conservative.

Development feasibility analysis determines whether projects succeed or fail, yet many developers continue using outdated templates or assumptions that don’t reflect Australian market reality. By incorporating the state-specific requirements, GST considerations, and realistic cost structures outlined in this guide, you position yourself to make more informed investment decisions and avoid the expensive mistakes that inadequate feasibility analysis often produces.