Section 24 Tax Impact Calculator
Quantify how Section 24 changes your tax bill as a higher-rate landlord. Compare the old full-deduction method against the current 20% credit and see the £ delta.
Why Section 24 matters
Before 2017, every £1 of buy-to-let mortgage interest reduced your taxable rental profit by £1. A higher-rate taxpayer saved 40p in tax for every £1 of interest. From the 2020/21 tax year, that full deduction was replaced with a flat 20% tax credit.
The effect: for higher-rate landlords with significant interest costs, the headline tax bill can now exceed the actual cash flow generated by the portfolio. Many landlords end up paying tax on income they don't really earn.
This calculator quantifies the cost. Compare the "pre-2017" column (what you'd be paying if the old rules applied) against the "current rules" column — the gap is the annual cost of Section 24 to you personally.
Save this calculation to your portfolio
Free account, no card required. Track every property, automate compliance, and let our AI engine surface your next high-leverage action.
Save & create free account