Updated for 2026/27

Section 24 Tax Calculator

See exactly how the Section 24 mortgage interest restriction affects your rental tax bill: your taxable profit, the flat-rate credit you receive on your mortgage interest, and how much extra tax you're paying compared with the old rules where interest was a deductible expense.

Tax year

Your results — 2026/27

Net tax on rental income

£2,786

Income tax on your rental profit, minus the Section 24 credit

Effective rate on rental income

22.11%

Net tax ÷ taxable rental profit

Taxable rental profit£12,600
Total taxable income£57,600
Income tax on rental profit£3,986
Section 24 tax credit− £1,200

Taxable rental profit is your rental income minus allowable running costs. Mortgage interest is not deducted here: instead it earns you a flat-rate credit, shown above, that's subtracted directly from your tax bill.

Compared with the old (pre-2020) rules

Before April 2020, mortgage interest was simply deducted from your rental income as an expense, like any other cost. Here's what your tax bill would look like if that were still the case.

Taxable profit under old rules£6,600
Tax due under old rules£1,586
Extra tax you pay because of Section 24 £1,200 / yr

The April 2027 property tax change, applied to your numbers

From 6 April 2027, property income moves onto its own higher rates (22%/42%/47%) and the Section 24 credit rises to 22%. Here's your net tax on rental income under 2026/27 rules versus 2027/28 rules, using the figures you've entered.

Net tax on rental income — 2026/27 rules£2,786
Net tax on rental income — 2027/28 rules£1,452
Extra annual tax from the April 2027 rate change -£1,334 / yr

Want the full picture, including how the Personal Allowance ordering change affects landlords with both a salary and rental income? Try the 2027 Tax Impact Calculator.

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Frequently asked questions

Section 24 of the Finance (No. 2) Act 2015, phased in fully by April 2020, stopped landlords deducting mortgage interest as a business expense. Instead, you pay tax on your full rental profit (rent minus allowable running costs, but not interest) and then receive a flat-rate tax credit worth a percentage of the interest you paid. For basic-rate taxpayers this often nets out similarly to the old rules, but for higher-rate taxpayers it can mean paying tax on income that has effectively already gone to the lender.