Rental Property Calculator UK
A complete UK buy-to-let model, cash flow, cap rate, cash-on-cash, IRR and the Section 24 finance-cost restriction, over your whole holding period.
Last updated: August 2026
£50,000, loan £150,000
Gross annual £14,400
of rent
of property value/yr
per year
per month
per month
Used for the Section 24 calculation below.
Year 1 cash flow
Cash invested
Over 10 years
Sale in year 10
CGT for individuals uses the £3,000 annual exempt amount and residential rates of 18% (basic) / 24% (higher). Company gains are taxed at Corporation Tax.
Year-by-year projection
| Year | Property value | Mortgage balance | NOI | Mortgage | Tax | After-tax CF |
|---|---|---|---|---|---|---|
| 1 | £200,000 | £146,907 | £9,508 | £10,523 | £2,317 | £-3,332 |
| 2 | £207,000 | £143,656 | £9,783 | £10,523 | £2,459 | £-3,198 |
| 3 | £214,245 | £140,239 | £10,066 | £10,523 | £2,606 | £-3,062 |
| 4 | £221,744 | £136,646 | £10,358 | £10,523 | £2,757 | £-2,922 |
| 5 | £229,505 | £132,870 | £10,657 | £10,523 | £2,914 | £-2,779 |
| 6 | £237,537 | £128,901 | £10,966 | £10,523 | £3,076 | £-2,633 |
| 7 | £245,851 | £124,729 | £11,283 | £10,523 | £3,243 | £-2,483 |
| 8 | £254,456 | £120,343 | £11,609 | £10,523 | £3,416 | £-2,330 |
| 9 | £263,362 | £115,733 | £11,944 | £10,523 | £3,595 | £-2,173 |
| 10 | £272,579 | £110,887 | £12,290 | £10,523 | £3,780 | £-2,013 |
How to read these numbers
Cap rate (NOI ÷ price) is the unleveraged property return, compare it on the dedicated Cap Rate Calculator. Cash-on-cash is your year-1 return on the actual cash you put in, including the equity you build through principal repayment. IRR blends every year's cash flow with the eventual sale into a single annualised return, the best single measure of a leveraged hold.
Section 24 is the single biggest reason UK buy-to-let maths changed. Since the 2017–2020 phase-out, individual landlords add all their rental income to their other income and pay tax on the profit before deducting mortgage interest, then receive only a 20% basic-rate credit on that interest. A higher-rate landlord therefore pays effectively 40% on income that funded a 5% mortgage, which is why many now buy through a limited company, where interest remains fully deductible.
Negative early-year cash flow is common for leveraged higher-rate landlords on repayment mortgages; the return then comes from principal paydown and capital growth rather than income. Stress-test by lowering appreciation and raising the mortgage rate to model a remortgage at renewal.
Educational tool, not financial or tax advice. Figures use 2026/27 UK tax rules. Always confirm your position with an accountant.
Related calculators
Other free UK tools that follow on from this calculation.
Cap Rate Calculator
Capitalisation rate, NOI ÷ property value, to compare UK rental properties like for like.
Buy-to-Let Calculator
Rental yield, ROI, SDLT surcharge and Section 24 mortgage interest restrictions.
Mortgage Calculator
Monthly repayments, total interest and LTV for any UK mortgage scenario.
Stamp Duty Calculator
SDLT for England & NI with post-April-2025 bands, plus Scotland LBTT and Wales LTT.
Mortgage Overpayment Calculator
See how regular or lump-sum overpayments cut your mortgage term and interest cost.
Reviewed by
Alexandre Bernier, LLM (UK), CFP®, CIM®, PFP®. Financial planner with 18 years in banking and wealth management, holding a UK master of laws and the Canadian CFP®, CIM® and PFP® designations. Writes and reviews every calculator and article on FinanceToolz.
Last updated: August 2026. How figures are sourced, reviewed and corrected is set out in our editorial policy. This is general information, not regulated financial advice.
Sources
Every rate and threshold used by this calculator is taken from the official pages below. If a figure here disagrees with one of these, the official page is right, please tell us.