Section 24 Mortgage Interest Relief: What Landlords Can and Cannot Claim

Tax Queen

Tax Expert @ Pie

4 min read

This guide explains how Section 24 of the Finance (No. 2) Act 2015 restricts mortgage interest relief for individual UK residential landlords. It details the transition from the old system, where finance costs were fully deductible, to the current framework where landlords receive a flat 20% basic-rate tax credit instead. The guide highlights the "stealth" tax effect where gross rental income can push landlords into higher tax brackets and provides clarity on what expenses remain fully deductible, such as maintenance and management fees. Finally, it outlines strategic considerations for compliance, including the potential benefits of incorporation for portfolio landlords.

The Reality of Modern Property Taxation

For property investors across the UK, managing a buy-to-let portfolio requires balancing operational overheads against an increasingly strict regulatory environment. The historical landscape allowed property owners to offset 100% of their finance costs directly against rental turnover before arriving at their taxable profit. However, structural modifications introduced by the government completely altered this paradigm.

At the heart of this legislative shift is Section 24 mortgage interest relief, a rule that transformed finance costs from a direct business expense into a restricted tax credit system. This single statutory change has pushed many unsuspecting property owners into higher income tax bands, making precise bookkeeping and strategic planning vital for survival. Understanding exactly how these calculations operate ensures you can protect your cash flow and avoid costly filing errors.

Mini house figures showing property taxation

What You Can Claim: The 20% Tax Credit

Under the fully implemented rules of Section 24 mortgage interest relief, you can no longer deduct your mortgage interest payments from your gross rental income to lower your taxable earnings. Instead, all individual landlords receive a basic-rate tax reduction.

HMRC grants a flat 20% tax credit based on your total finance costs. For instance, if your property mortgage interest totals £5,000 across the financial year, you cannot use that amount to lower your declared rental profits. Instead, you calculate your income tax on the full revenue, then subtract a £1,000 credit (£5,000 multiplied by 20%) directly from your final personal tax liability.

This restriction applies strictly to residential properties held in personal names. It covers not just standard bank mortgage interest, but also alternative financing vehicles such as interest on loans taken out to refurbish a property, overdraft fees, and bridging finance options. To ensure these deductions are handled accurately on your property schedule, you can follow a clear walkthrough on how to add mortgage interest in the Pie App.

Landlord holding documents while renovating his property

What You Cannot Claim: Direct Profit Reductions

The most dangerous trap involving Section 24 mortgage interest relief is the artificial inflation of your net income profile. Because your finance costs are ignored during the initial calculation of your net taxable income, your paper profits look significantly higher than your actual take-home cash.

You cannot use the following elements to reduce your gross rental income on your main tax returns:

The Principal Loan Repayment: Capital repayment portions of a repayment mortgage have never been tax-deductible, and this remains unchanged.

The Mortgage Interest Element: As established, the interest component must be declared fully and can only be recovered via the basic rate reduction.

This artificial inflation of your gross income means that basic-rate taxpayers are frequently pushed into the higher 40% tax bracket without actually taking home any extra money. This phenomenon can strip away your eligibility for certain family allowances and personal thresholds. If you want to model your exact position, you can map your figures safely using an interactive rental tax calculator.

Permitted Allowable Expenses Outside Section 24

While finance costs face strict limitations, you can still deduct standard day-to-day operational expenses directly from your rental turnover. Maximising these legitimate write-offs is one of the most effective strategies to lower your overall liability.

Legitimate property expenses include letting agent commissions, landlord insurance policies, utility bills left unpaid by tenants, and direct maintenance costs that do not add capital value. When filing your year-end property declarations, all of these operational figures must be consolidated onto the required SA105 property income form. For a broader overview of how to optimise your setup, it is useful to reference an essential guide to tax for UK landlords.

Landlords shaking hands with their accountant

Pie Tax: Simplifying Landlord Tax Compliance

Navigating restricted tax credits alongside monthly rental statements does not have to be a stressful administrative burden. Pie Tax is engineered to automate property record-keeping cleanly and accurately.

Ready to take the guesswork out of your property portfolio? Discover why Pie is trusted by modern landlords across the UK, or download Pie today to keep your property tax returns perfectly compliant.