Buy-to-Let Landlord Tax Return Checklist for 2026/27
A complete Self Assessment checklist for UK buy-to-let landlords in 2026/27 — income, allowable expenses, the mortgage interest tax credit, and key deadlines.
The annual checklist
Buy-to-let tax has become more complex since Section 24 phased out direct mortgage interest relief for individual landlords, and getting the mechanics right — especially the interest tax credit — makes a real difference to what you actually owe. Here's a practical run-through of what to gather and check each year.
Buy-to-Let Calculator
Analyse the profitability of a buy-to-let investment including tax and costs.
Open Buy-to-Let calculator1. Gather your income records
- Total rent received across the tax year (6 April to 5 April), from all rental properties combined
- Any additional income related to the letting — for example, a non-refundable deposit deduction retained for damage, or charges to tenants for specific services
2. Gather your allowable expenses
- Letting agent management and finding fees
- Landlord (buildings, contents, rent guarantee) insurance
- General repairs and maintenance (not capital improvements)
- Ground rent and service charges for leasehold properties
- Accountancy and professional fees related to the letting
- Utility bills you pay as landlord (common in HMOs or void periods)
- Council tax paid by you during void periods
- Advertising costs for finding tenants
- Legal fees for tenancy-related matters (not for buying/selling the property)
3. Calculate the mortgage interest tax credit
Since Section 24 fully phased in, mortgage interest for individual landlords works differently from other expenses:
Step 1: Calculate rental profit without deducting mortgage interest (deduct all other allowable expenses as normal).
Step 2: Calculate tax on that profit at your marginal rate.
Step 3: Apply a tax credit worth 20% of the mortgage interest actually paid during the year, reducing your tax bill directly.
This means a higher-rate (40%) taxpayer effectively only gets relief at 20% on their mortgage interest, not 40% — a significant shift from the old system where interest was deducted before calculating taxable profit.
Income Tax Calculator
Work out how much income tax you owe using the latest 2025/26 UK tax bands.
Open Income Tax calculatorWorked example: higher-rate taxpayer landlord
Rental income: £15,600/year Allowable expenses (excluding mortgage interest): £3,200 Mortgage interest paid: £5,400
Taxable rental profit: £15,600 − £3,200 = £12,400 (mortgage interest not deducted here)
Tax on £12,400 at 40% (higher rate, assuming other income already uses the basic rate band): £4,960
Mortgage interest tax credit: £5,400 × 20% = £1,080
Net tax due on rental income: £4,960 − £1,080 = £3,880
Under the old system (full deduction at 40%), the same landlord would have paid tax on £15,600 − £3,200 − £5,400 = £7,000 at 40% = £2,800 — meaningfully less than the £3,880 due under current rules, illustrating why Section 24 increased tax bills for higher-rate individual landlords specifically.
4. Check whether replacement of domestic items relief applies
If you let a furnished property and replaced items like a sofa, bed, or washing machine on a like-for-like basis, the replacement cost is deductible — but the cost of the original item when you first furnished the property isn't, and upgrading to a noticeably better item is only deductible up to the cost of an equivalent replacement.
5. Decide: actual expenses or the £1,000 property allowance?
If your total allowable expenses (excluding mortgage interest, since that's handled separately via the credit) come to less than £1,000, the flat property allowance may give a better outcome than itemising — run both calculations to check.
6. File and pay on time
- Register for Self Assessment by 5 October following the tax year you first had rental income, if not already registered
- File online by 31 January following the tax year end
- Pay any tax owed, including relevant Payments on Account for the following year, by the same date
The bottom line
The single most common landlord tax mistake since Section 24 is treating mortgage interest as a normal deductible expense rather than running it through the separate 20% credit calculation — get this step right, keep clean records of income and expenses throughout the year, and the rest of the Self Assessment process for a straightforward buy-to-let is fairly mechanical.
Frequently asked questions
Do all landlords need to complete a Self Assessment tax return?
If you receive rental income above £1,000 in a tax year (before expenses), you generally need to register for and complete Self Assessment, reporting the income on the property pages (SA105) of your return, even if your actual profit after expenses is small or nil.
What allowable expenses can a landlord deduct from rental income?
Common allowable expenses include letting agent fees, landlord insurance, general maintenance and repairs (not improvements), ground rent and service charges, accountancy fees, and utility bills paid by the landlord rather than the tenant — full mortgage interest is no longer directly deductible for individual landlords, but is given as a 20% tax credit instead.
How does the mortgage interest tax credit work for landlords?
Since the Section 24 changes were fully phased in, individual landlords can't deduct mortgage interest directly from rental income. Instead, they get a tax credit worth 20% of the mortgage interest paid, applied after calculating tax on the full rental profit — this particularly reduces the benefit for higher and additional-rate taxpayers compared with the old system of direct deduction.
Can I claim for a new kitchen or bathroom as a landlord?
Replacing an existing kitchen or bathroom on a like-for-like basis is generally deductible as a repair, but upgrading to a significantly better standard (adding features that weren't there before) is usually treated as a capital improvement, which isn't deductible against rental income but reduces Capital Gains Tax when you eventually sell.
What is the replacement of domestic items relief?
This allows landlords to deduct the cost of replacing furnishings (beds, sofas, white goods, curtains, carpets) provided in a furnished let, on a like-for-like basis, capped at the cost of an equivalent modern replacement if you upgrade to something better.
Do I need to declare rental income if I made a loss?
Yes, if your gross rental income exceeds £1,000, you still need to report it even if allowable expenses mean you made a loss. Reporting a loss also lets you carry it forward to offset against future rental profits, which is worth doing even when no tax is currently due.
What records should a landlord keep for their tax return?
Keep all rent received records, invoices and receipts for expenses, mortgage interest statements from your lender, letting agent statements, and evidence of any capital expenditure — HMRC can request these going back several years, and good records also make it far easier to complete the return accurately each year.
When is the Self Assessment deadline for landlords?
The same as all Self Assessment taxpayers — register for Self Assessment by 5 October following the end of the tax year in which you first had rental income, file your return online by 31 January, and pay any tax owed by the same date.
Can landlords use the £1,000 property allowance instead of claiming actual expenses?
Yes — landlords with gross rental income under £1,000 don't need to report it at all, and those with modest expenses can deduct the flat £1,000 property allowance instead of itemising actual costs, though this is usually only beneficial if your actual allowable expenses are lower than £1,000.
Do landlords need to pay Class 2 or Class 4 National Insurance on rental income?
Generally no — rental income from letting property is treated as investment income, not trading income, so it doesn't attract Class 2 or Class 4 National Insurance in most cases, unlike genuinely self-employed trading profits.
Try the calculators
Buy-to-Let Calculator
Analyse the profitability of a buy-to-let investment including tax and costs.
Income Tax Calculator
Work out how much income tax you owe using the latest 2025/26 UK tax bands.
Self-Employed Tax Calculator
Calculate income tax, Class 2 and Class 4 National Insurance for self-employed and sole traders for 2025/26.
Related reading
Renting to Family Members Below Market Rent: Tax Implications 2026/27
How UK tax rules treat letting a property to family below market rent in 2026/27 — restricted expense deductions, Capital Gains Tax, and mortgage considerations.
Making Tax Digital for Landlords: A 2026 Survival Guide
MTD for Income Tax lands for landlords from April 2026. Learn who is in scope, the quarterly filing rhythm, software rules and how to prepare.
Replacement of Domestic Items Relief: Landlord Guide 2026
How UK landlords claim replacement of domestic items relief in 2026/27 - what qualifies, the like-for-like rule, and how it cuts your rental tax bill.