The UK tax year ends on April 5, and the weeks leading up to that date represent a critical window for property investors to optimise their tax position. Unlike the Australian financial year that concludes on June 30, UK landlords and buy-to-let investors must align their tax planning with HMRC’s calendar to maximise deductions, use annual allowances that do not carry forward, and ensure their self-assessment returns reflect legitimate tax-saving opportunities.

This guide walks through the essential tax planning steps UK property investors should complete before April 5, covering rental income reporting, capital gains tax considerations, allowable expenses under current mortgage interest relief rules, and record-keeping requirements that will support your self-assessment filing.

What You Will Learn

You will learn how to review your rental income and expenses before the tax year closes, identify allowable deductions under the restricted mortgage interest relief rules (Section 24), decide whether to use your annual capital gains tax exemption, ensure you meet HMRC record-keeping standards, and prepare for payment on account obligations. This article also covers common mistakes buy-to-let landlords make when filing self-assessment returns and answers frequently asked questions about property tax planning in the UK context.

The information provided is general educational guidance and not personalised tax, financial, or legal advice. Tax rules are complex, change regularly, and depend on your individual circumstances. Consider consulting an accountant, tax adviser, or HMRC directly for advice specific to your situation.

Step 1: Review Your Rental Income and Expenses for the Tax Year

The first task is to compile a complete record of rental income received and allowable expenses paid between April 6 of the previous year and April 5 of the current year. According to HMRC guidance on renting out a property, you must report all rent and other payments from tenants, including advance rent, deposits you retain, and payments for services you provide.

Allowable expenses you can deduct against rental income include letting agent fees, buildings and contents insurance, maintenance and repairs (but not improvements), utility bills you pay (if not recharged to tenants), council tax and ground rent, and services such as gardening or cleaning for communal areas. Since April 2020, mortgage interest is no longer deductible as an expense in the usual way. Instead, you receive a 20 per cent tax credit on your mortgage interest costs, regardless of whether you are a basic-rate, higher-rate, or additional-rate taxpayer. This change, known as Section 24, means your taxable rental profit is calculated before deducting mortgage interest, which can push some landlords into a higher tax bracket.

Before April 5, gather all invoices, receipts, bank statements, and tenancy agreements. If you have multiple properties, organise records by property to make your self-assessment return easier to complete. HMRC may ask to see these records during an enquiry, and you are required to keep them for at least five years after the January 31 self-assessment deadline (so until January 31, 2032, for the 2025 to 2026 tax year).

Step 2: Identify Legitimate Deductions You May Have Missed

Many buy-to-let landlords fail to claim all the allowable expenses to which they are entitled. Before the tax year ends, review the following categories to ensure you have not overlooked deductible costs:

Professional fees: Accountant fees for preparing your rental accounts and tax return, legal fees for renewing a lease (not the initial purchase), and solicitor costs for evicting a tenant are all allowable.

Travel costs: If you travel to your rental property for maintenance, to collect rent, or to manage the letting, you can deduct mileage at HMRC’s approved rates (45p per mile for the first 10,000 miles, 25p thereafter for 2025 to 2026) or actual costs such as fuel, parking, and public transport. Keep a log showing the date, purpose, mileage, and destination.

Replacing domestic items: For furnished lettings, you can deduct the cost of replacing furnishings, appliances, kitchenware, and similar domestic items (the replacements-only rule applies, not initial purchase costs).

Property allowance: If your total rental income before expenses is £1,000 or less in the tax year, you can claim the property allowance and pay no tax on that income without needing to report it. If your income is above £1,000, you can either deduct actual expenses or claim the £1,000 allowance instead of expenses (but not both). The allowance rarely benefits landlords with significant costs, but it simplifies reporting for those with low rental income.

Pre-letting expenses: Costs incurred up to seven days before a new letting begins (advertising, referencing, minor repairs) are allowable, provided the expense would be allowable during the tenancy.

Review your bank and credit card statements for the tax year to identify any overlooked deductible payments. If you discover a missed expense after April 5, you can still include it in your self-assessment return (due by January 31 the following year), but acting now gives you time to obtain duplicate receipts if originals are missing.

Step 3: Decide Whether to Realise or Defer Capital Gains

If you are considering selling a buy-to-let property, the timing of completion can significantly affect your capital gains tax (CGT) bill. Each individual has an annual CGT exemption (the annual exempt amount), which for the 2025 to 2026 tax year is £3,000. This allowance does not carry forward, so if you do not use it before April 5, you lose it.

According to HMRC guidance on capital gains tax, CGT is charged on the gain you make when you dispose of a property that is not your main home. The gain is the sale price minus the purchase price, minus allowable costs such as solicitor fees, estate agent fees, stamp duty paid on purchase, and the cost of improvements (not repairs). If your gain after deducting these costs exceeds the annual exemption, you pay CGT at 18 per cent (basic-rate taxpayer) or 24 per cent (higher or additional-rate) on residential property as of 2025 to 2026 rates; verify current rates with HMRC or a tax adviser before deciding.

If you expect to sell a property soon and your gain will be close to the annual exemption threshold, completing the sale before April 5 allows you to use this year’s allowance. If the gain is much larger, you might consider splitting the disposal across two tax years (for example, exchanging contracts in one year and completing in the next, or selling multiple properties in different years) to use two annual exemptions. However, the date of disposal for CGT purposes is usually the date of completion (when legal title transfers), not the date contracts are exchanged, so you cannot easily manipulate the timing once contracts are signed.

Alternatively, if your income is unusually high this tax year and you expect to drop to the basic-rate band next year, deferring a sale until after April 5 may result in a lower CGT rate on the portion of the gain above the exemption.

You must report and pay capital gains tax on UK residential property within 60 days of completion. This is separate from your self-assessment return and requires submitting a residential property return and payment to HMRC even if you do not normally complete self-assessment.

Step 4: Prepare for Payment on Account Obligations

If your self-assessment tax bill for the previous year exceeded £1,000 and less than 80 per cent of the tax was deducted at source, HMRC will require you to make payments on account for the current tax year. These are advance payments towards your next tax bill, each equal to half of the previous year’s liability, due on January 31 (during the tax year) and July 31 (after the tax year ends).

For example, if your 2024 to 2025 self-assessment tax bill (filed by January 31, 2026) was £8,000, HMRC will expect two payments on account of £4,000 each for the 2025 to 2026 tax year, due on January 31, 2026, and July 31, 2026. When you file your 2025 to 2026 return by January 31, 2027, any balance over the £8,000 already paid on account is due immediately (the balancing payment), and a new set of payments on account begins for 2026 to 2027.

Before April 5, estimate your tax liability for the current year. If you expect your rental profit to be significantly lower than last year (perhaps because of higher expenses, a void period, or a property sale that will not recur), you can apply to reduce your payments on account. Use HMRC’s online self-assessment account or form SA303 to request a reduction. If you reduce payments on account and your actual liability turns out to be higher, HMRC will charge interest on the underpaid amount, so only reduce if you are confident income has genuinely fallen.

Conversely, if your rental income or capital gains have increased substantially this year, set aside additional funds now to cover the higher tax bill and avoid a cash-flow shock in January.

Step 5: Check Your Record-Keeping and HMRC Registration Status

HMRC requires landlords to keep records of all rental income and expenses, including bank statements, invoices, receipts, tenancy agreements, and mortgage statements. If you have not been keeping digital or paper records throughout the year, April 5 is your deadline to reconstruct missing records while the tax year is still open and third parties (letting agents, tenants, suppliers) can provide duplicate statements or receipts.

If you became a landlord during this tax year and have not yet registered for self-assessment, you must notify HMRC by October 5 following the end of the tax year in which you first received rental income. For example, if you first let a property in July 2025 (during the 2025 to 2026 tax year ending April 5, 2026), you must register by October 5, 2026. Registering early (before April 5) gives you more time to understand the self-assessment process and avoid a late-registration penalty.

If your rental income is generated through a limited company rather than in your personal name, different rules apply (corporation tax, not income tax, and different filing deadlines). This article addresses individual landlords only. Company landlords should consult an accountant before the company’s accounting period ends.

Common Mistakes to Avoid

Claiming improvement costs as repairs: Repairs restore a property to its original condition and are deductible. Improvements enhance the property beyond its original state and are not deductible against rental income (though they reduce capital gains tax when you sell). Repainting a room is a repair; adding an extension is an improvement. HMRC scrutinises this distinction closely.

Deducting mortgage capital repayments: Only the interest portion of your mortgage payment qualifies for the 20 per cent tax credit. Repayments of the loan capital are not deductible. Check your annual mortgage statement to separate interest from capital.

Mixing personal and rental use: If you use a property partly as your own home and partly for letting, you can only deduct the proportion of expenses attributable to the rental use. HMRC will disallow expenses that relate to your personal benefit.

Failing to report cash rent: All rental income must be reported, whether received by bank transfer, cheque, or cash. Underreporting rental income is tax evasion and HMRC has data-sharing agreements with letting platforms, estate agents, and Land Registry records to cross-check reported income.

Not claiming the rent-a-room relief when eligible: If you let a room in your main home to a lodger and the gross receipts are £7,500 or less per year (2025 to 2026), you can claim rent-a-room relief and pay no tax on that income. This is separate from the property allowance and applies only to letting in your own home.

Frequently Asked Questions

When is the deadline to file my self-assessment tax return?
For the tax year ending April 5, 2026, the online self-assessment deadline is January 31, 2027. Paper returns must be filed by October 31, 2026. Any tax owed is also due by January 31, 2027.

What happens if I miss the April 5 deadline for using my capital gains tax allowance?
The annual exempt amount (£3,000 for 2025 to 2026) does not carry forward. If you do not use it by disposing of an asset before April 5, you lose it. The following tax year brings a new £3,000 allowance (subject to any changes announced in the Budget).

Can I deduct the cost of mortgage interest in full?
No. Since April 2020, mortgage interest is not deductible as an expense when calculating rental profit. Instead, you receive a 20 per cent tax credit on your mortgage interest costs, applied after your tax liability is calculated. This means higher-rate and additional-rate taxpayers no longer receive relief at their marginal rate.

Do I need to register for self-assessment if my rental income is below the property allowance?
If your gross rental income is £1,000 or less and you claim the property allowance, you do not need to report it or register for self-assessment. If your income exceeds £1,000, you must register and file a return even if your profit after expenses is nil or negative.

How do I know if I need to make payments on account?
HMRC will tell you after you file your self-assessment return if payments on account are required for the following year. Generally, if your previous year’s tax bill was over £1,000 and less than 80 per cent was collected at source (via PAYE, for example), you will make payments on account.

Conclusion

Effective tax planning before the April 5 deadline can reduce your liability, ensure you claim all allowable deductions, and avoid penalties for late filing or underpayment. Review your rental income and expenses now, identify overlooked deductions, consider the timing of any property sales to make best use of your capital gains tax annual exemption, and prepare for payment on account obligations if they apply to you.

The information in this article is general educational guidance and not personalised tax, financial, or legal advice. Tax rules are complex, change frequently, and depend on your individual circumstances, the structure of your property portfolio, and your other sources of income. Consult an accountant, tax adviser, or HMRC directly for advice specific to your situation before making tax planning decisions. Visit GOV.UK Self Assessment and MoneyHelper for further guidance on reporting rental income and meeting your obligations to HMRC.

Your home may be repossessed if you do not keep up repayments on your mortgage.