What is Section 24 costing me, and when does MTD start?
Mortgage interest stopped being deductible years ago and quarterly reporting is already live for 864,000 people. Seven steps show what the restriction costs you and which phase catches you.
Why this exists: 864,000 in scope now · 2.9m by 2028. Typically £500–£6,000 of clarity.
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Rates as at 6 April 2026 — the 2026/27 tax year.
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The rules behind this
Every figure above comes from one of these. Where the tool has interpreted rather than calculated, it says so in the finding.
Finance costs on residential property are not deductible for individuals; relief is a basic-rate tax reduction.
The tax reduction is 20% of the lower of finance costs, property profits, and income above the personal allowance.
Making Tax Digital for Income Tax applies by qualifying income — gross, not profit — from April 2026, 2027 and 2028.
Jointly held property of a married couple is taxed 50/50 unless form 17 is filed.
UK residential property gains must be reported and paid within 60 days of completion.
Questions people ask
Why can I not deduct my mortgage interest?
Section 24 phased it out between 2017 and 2020. You are taxed on rent less running costs, then given a credit worth 20% of the interest. For a basic-rate landlord that is the same as before; for a higher-rate one it means paying tax on money the lender took.
Is MTD really based on gross rent?
Yes, and it is the detail that surprises people most. £55,000 of rent with a £45,000 mortgage is £10,000 of real profit and still inside the April 2026 phase.
Should I move my properties into a company?
Rarely for ones you already own. The transfer is a disposal at market value, so capital gains tax and higher-rate stamp duty both fall due, and those one-off costs commonly take decades of annual saving to recover. The question is really about what you buy next.
Which year decides my MTD date?
The tax year two years before the phase starts. April 2026 is judged on 2024/25 income — which has already happened, so there is nothing left to change, only to prepare for.
What can I claim that I probably am not?
Replacement of domestic items, mileage to the property, a share of home office costs, professional and accountancy fees, and safety certificates. None are exotic; all are commonly left out.