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What Section 24 really costs your rental.
See exactly what the mortgage-interest relief restriction does to your tax bill — the tax under Section 24 versus the old rules, the extra it costs you each year, and the profit you actually keep after tax.
- 2025/26 bands
- Old rules vs new
- Post-tax profit
How it works
Enter your figures
Rent, expenses, interest and other income.
Compare the rules
Old deductible rules vs Section 24.
See the impact
Extra tax and the profit you keep.
What you'll see
- The extra tax Section 24 costs you each year
- Your tax under the old rules vs the new rules
- Post-tax rental profit and effective tax rate
- A plain-English read on how hard you are hit
Your figures
Enter your year
Extra tax from Section 24
£0
per year vs the pre-2017 rules
Post-tax profit
£0
68% effective tax on rental profit
Section 24 adds £1,400 of tax a year (effective 68% on your rental profit). Still profitable after tax.
Old rules vs Section 24
Your tax bill, compared
The same year, taxed both ways — what the relief restriction adds to your bill.
What this means
- Section 24 costs you an extra £1,400 in tax a year versus the old rules.
- Estimate only — England/NI & Wales bands, individual landlord. Verify with an accountant.
Buying another rental?
Section 24 squeezes leveraged landlords. Before you add to the portfolio, check the property's risks and the numbers behind the deal.
This calculator is for guidance only and does not constitute financial, tax, mortgage or investment advice. Figures are estimates — always seek professional advice and verify costs before committing to a purchase.
Section 24 — common questions
- What is Section 24?
- Section 24 of the Finance Act 2015 phased out the ability of individual landlords to deduct mortgage interest from rental income before tax. Instead you pay tax on the full rental profit and get a flat 20% tax credit on your finance costs. Basic-rate taxpayers are usually unaffected; higher and additional-rate taxpayers pay more.
- Does Section 24 affect basic-rate taxpayers?
- Generally no — the 20% credit matches the 20% basic rate, so the restriction is neutral. The catch is that adding the full rental profit to your income can tip you into the higher-rate band, which the calculator accounts for.
- Does Section 24 apply to limited companies?
- No. Section 24 only applies to individual landlords. Properties held in a limited company can still deduct mortgage interest as a business expense, which is one reason many landlords incorporate — though incorporation has its own costs and tax consequences. Always take advice.
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