Mortgage interest tax relief (Section 24) & rental income tax (UK)

Mortgage interest tax relief (Section 24) can change UK rental income tax outcomes. This guide explains key caveats and how to use this MVP estimator as a simplified baseline, then verify using official guidance.

Why Section 24 comes up in searches

Mortgage interest treatment can materially affect a landlord's final tax outcome. People searching "mortgage interest" often want to know how much the interest reduces taxable income or tax due.

Important limitation

This MVP rental estimator does not model mortgage interest relief (Section 24). It estimates incremental Income Tax from net rental profit using selected tax-year bands.

How to use this estimator anyway

Use the result as a baseline planning estimate, then verify your mortgage interest treatment using official guidance or an accountant if Section 24 applies to you.

Last updated: 2026-04-20

FAQ

Does the calculator include Section 24?

No. This MVP does not model mortgage interest relief (Section 24).

Should I subtract mortgage interest as an expense here?

Use official guidance to determine what is allowable in your case. This tool expects net profit, but does not guarantee that a given item is allowable.

Is the estimate still useful?

Yes for a simplified baseline (marginal-rate intuition), but you must verify final liability if mortgage interest relief applies.