What’s Inside
- One tab per property (three included, easy to duplicate for more) — log every transaction against the exact SA105 expense category.
- Section 24 handled correctly — residential mortgage interest is kept in its own column, separate from deductible expenses, exactly as HMRC requires.
- SA105 Summary tab — totals every property together, box by box, plus your adjusted profit and the 20% Section 24 tax reduction — ready for your return or your accountant.
- Example rows included to show the expected format.
Why Section 24 Trips People Up
Since April 2020, mortgage interest on a residential letting is no longer deducted from your rental profit. Instead, it earns a flat 20% tax credit against your bill — regardless of whether you’re a basic, higher or additional rate taxpayer. Get this wrong and you either overstate your profit (and overpay tax) or claim relief you're not entitled to. This spreadsheet keeps residential mortgage interest in its own labelled column so it can never accidentally get mixed into your deductible expenses.
Loan interest on a non-residential property (e.g. a commercial unit) is unaffected by Section 24 and remains a normal, fully deductible expense — that goes in a separate column too.
Frequently Asked Questions
Since April 2020, mortgage interest on residential lettings is no longer deductible from rental profit. Instead, you get a tax reduction equal to 20% of the interest paid, applied to your tax bill via SA105 box 44 — regardless of your tax band. Non-residential property loan interest remains fully deductible in box 26.
Box 24 (rent, rates, insurance, ground rents), Box 25 (repairs & maintenance), Box 26 (non-residential loan interest), Box 27 (legal, management & professional fees), Box 28 (services provided), Box 29 (other allowable expenses), Box 36 (replacing domestic items), and Box 44 (residential finance costs / Section 24).
No — this workbook has a separate tab per property (three included, duplicate the tab for more) and one Summary tab that totals everything together automatically for your tax return.
Yes — completely free, no email signup, no registration. Built by PayToolkit, the free UK tax calculator site.
Sources
- Expense categories and box numbers from GOV.UK — SA105 UK Property Notes 2026 (checked July 2026)
- Section 24 rules from GOV.UK — Changes to tax relief for residential landlords