UK Property Flip ROI Calculator (2026)

Model the full P&L of a UK refurb-to-resale: SDLT, bridging finance, holding costs, selling costs, tax, and the Maximum Allowable Offer back-solved from your target margin. Built for developers who price discipline matters to.

UK Property Flip ROI Calculator 2026

Cash, bridging, MAO, holding costs and tax — modelled on a single refurb-to-resale project. England and Northern Ireland; April 2025 SDLT rates.

Project

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Finance

Tax & Target

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Used to back-solve the Maximum Allowable Offer (MAO).

Project Diagnostic

Estimated SDLT£10,100
Total Holding Cost£2,700
Selling Costs (2.5% of ARV)£7,125
Total Project Cost£229,800
Cash Into Deal£229,800
Gross Profit£48,075
Tax Due-£12,019
MAO at 20% Target Margin£181,647
Net Profit
£36,056
16.9% margin on GDV · 20.9% margin on cost
Total ROI on Cash15.7%
Annualised ROI33.8%

Illustrative model only. Assumes interest is rolled up on bridging finance and repaid at exit. SDLT estimate uses the April 2025 additional-dwelling schedule and excludes the non-UK resident surcharge. Individual flipping is treated as trading income (income tax plus Class 4 National Insurance applied at a flat 6% approximation on profit) — actual NI is banded and depends on total earnings. Limited company flipping is taxed at 25% corporation tax with no small-profits or marginal relief modelled. ARV is your assumed sale price, not a guarantee. Capital at risk in any property project. Shaded Canvas is not authorised by the FCA and does not provide tax or mortgage advice.

How the Flip ROI Calculator Works

The calculator runs a complete single-project P&L. Acquisition costs are computed from your purchase price using the April 2025 additional-dwelling SDLT schedule, plus a fixed legal and survey allowance. The refurb budget you supply is added at face value, and monthly holding costs (utilities, council tax, insurance, ground rent or service charge) are multiplied by your project duration to produce total carry.

If bridging finance is selected, the loan size is purchase price times LTV, interest is computed on the monthly rate across the full duration (rolled up to exit, as is standard for UK bridging), and the arrangement fee is added as an up-front cost. On exit, the calculator deducts selling costs as a percentage of ARV — typically 1.5% agent commission plus 1% legal and marketing — and applies tax to the gross profit.

The MAO solver

Maximum Allowable Offer is solved iteratively because two inputs depend on the purchase price itself: SDLT (banded) and bridging interest (LTV-scaled). The calculator runs a fixed-point iteration until MAO converges within £1, then displays the result alongside the live P&L for the purchase price you typed. Bidding at or below MAO is the operational discipline that separates profitable flippers from the long tail.

What Senior Investors Get Wrong About Flips

UK property flips look simple in pitch decks and devastating in spreadsheets. The five places amateur capital evaporates, predictably:

  • SDLT understatement — the additional-dwelling surcharge adds £15,000–£25,000 to a typical northern flip. Many models still use the standard schedule.
  • Holding cost smoothing — council tax, utilities, insurance, and (on bridged deals) interest compound monthly. A two-month overrun on a six-month project is a 33% increase in carry.
  • Refurb cost creep — UK refurb projects routinely overrun budget by 15-25%. The calculator surfaces the raw inputs so you can model contingency directly into the refurb figure.
  • Bridging arithmetic — monthly bridging at 0.95% per month is 11.4% annualised. On a £150k loan over 9 months, that is £12,825 of pure carry — independent of arrangement fees.
  • Tax on profit — individual flippers pay income tax plus Class 4 NI on trading profit, not CGT. The difference can be 20+ percentage points of net margin for higher-rate taxpayers.

For senior professionals modelling whether to deploy six figures into a flip versus a passive route, the tax leg alone usually settles it. A higher-rate individual netting £50,000 gross profit on a six-month flip keeps roughly £27,000 after income tax and NI. The same capital in Model One generates a comparable net return with zero project risk.

Worked Example — Default Scenario

With the calculator's defaults — £180,000 purchase, £35,000 refurb, £285,000 ARV, six-month duration, £450 per month holding, 2.5% selling costs, cash purchase, limited company:

  • SDLT (additional dwelling, April 2025): £10,100
  • Legal and survey: £2,000
  • Total holding cost (6 mo × £450): £2,700
  • Selling costs (2.5% × £285k): £7,125
  • Total project cost: £229,800
  • Gross profit: £48,075 (16.9% margin on GDV · 20.9% margin on cost)
  • Corporation tax (25%): £12,019
  • Net profit: £36,056
  • Annualised ROI on cash: 33.8%

Switch funding to bridging at 70% LTV, 0.95%/month, 2% arrangement fee and the picture changes materially. The arrangement fee adds ~£2,520, interest adds ~£7,182, and total project cost rises to ~£239,502. Gross profit compresses to ~£38,373 and margin on cost drops to ~16.0%. The annualised ROI on the smaller cash stake can still look strong, but the deal sits much closer to the line.

When Flipping Makes Sense

Flipping is a margin-on-cost trade with timing risk. It rewards three things: deep buy-side discipline (MAO enforcement), refurb execution speed, and accurate ARV reading in the specific sub-market. For senior professionals modelling deployment, flipping competes with passive income strategies on a risk-adjusted basis — and the calculator's outputs are designed to make that comparison legible.

If you are testing whether to flip rather than hold, UK buy-to-let economics and the BTL yield calculator are the natural counterparts. If you are testing whether to flip rather than deploy passively, Model One is the unleveraged income route this calculator's defaults benchmark against.

Related Reading

Frequently Asked Questions

What does this flip ROI calculator do?
It models a complete UK refurb-to-resale project in one view: SDLT and acquisition fees, refurb budget, monthly holding costs, bridging finance (interest plus arrangement fee) if used, selling costs on exit, and post-tax net profit. It also computes Maximum Allowable Offer (MAO) — the highest purchase price that hits your target margin on cost — and reports total ROI on cash, annualised ROI, margin on GDV, and margin on cost.
What is MAO and why does it matter?
MAO stands for Maximum Allowable Offer. It is the highest price you can pay for a property while still hitting your target margin once all costs are factored in. Disciplined flippers set a target margin first — typically 20% to 30% on cost — and back-solve MAO. Bidding above MAO is the single most common reason flips lose money. The calculator computes MAO iteratively because SDLT and bridging interest both depend on the purchase price.
Does the calculator handle bridging finance properly?
Yes. Switch the funding source to Bridging and supply the LTV, monthly rate, and arrangement fee. The calculator assumes interest is rolled up across the project duration and repaid at exit, which is the standard UK bridging structure. The arrangement fee is added to total project cost; interest accrues linearly across the duration you set. Both the MAO solver and the headline P&L take bridging into account.
How is tax calculated?
Two ownership paths. Limited company / SPV: profit taxed at 25% corporation tax flat (small-profits rate and marginal relief are not modelled, so this is a conservative upper bound for small portfolios). Individual: HMRC treats flipping as trading income, so profit is subject to income tax at your marginal band plus Class 4 National Insurance — approximated at a flat 6% on profit. Actual NI is banded and depends on total earnings; a tax adviser should confirm the exact figure for a real project.
What SDLT rate does it apply?
The April 2025 additional-dwelling schedule for England and Northern Ireland — standard SDLT bands plus a 5% surcharge on every band, applied when the price is £40,000 or more. This is the correct schedule for both individual flippers (who almost always own a main residence already) and non-natural-person purchasers like limited companies. The non-UK resident 2% surcharge is not included.
Why does the default scenario show a slim margin?
The defaults — £180k purchase, £35k refurb, £285k ARV, six months, cash — produce roughly a 21% margin on cost before tax. That is the realistic floor for a UK flip in 2026. Once you switch to bridging or extend the duration, the margin compresses fast. The tool is calibrated to make that compression visible: many UK flips look profitable on paper at acquisition but lose 5-10 percentage points of margin to overrun in duration, bridging interest, and refurb creep.
What is the difference between margin on GDV and margin on cost?
Margin on GDV (Gross Development Value) is profit divided by ARV — the percentage of the sale price that ends up as profit. Margin on cost is profit divided by total project cost — the return generated on every pound spent. UK flippers typically target 20% on cost or 15% on GDV; institutional developers usually target 17-20% on GDV. Margin on cost is the more honest measure because it tells you what return you earned on capital actually deployed.
Is this regulated tax or financial advice?
No. The calculator is an illustrative model. Shaded Canvas is not authorised by the FCA and does not provide tax, mortgage or investment advice. Tax treatment depends on individual circumstances, the structure of the deal, and whether HMRC classes the activity as trading. Bridging availability and pricing depend on lender criteria. Speak to a qualified tax adviser and a regulated mortgage broker before transacting.

Considering a flip but uncertain on the return?

See how Shaded Canvas helps senior professionals deploy capital into asset-backed UK property income — comparable net returns without project, refurb, or sell-side risk.

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