Section 24 Tax for Buy to Let in the UK, Explained

What Is Section 24 and How Does It Work?

Section 24 refers to a change in UK tax law affecting how individual landlords account for mortgage interest and other finance costs on residential buy-to-let properties. Before this legislation, landlords could deduct their full mortgage interest from their rental income before calculating the tax they owed. This meant that if a property generated rental income but carried a large mortgage, the interest reduced the taxable profit directly, which was especially valuable for higher-rate and additional-rate taxpayers. Section 24 removed that ability for individually held properties. Instead of deducting finance costs from rental income, landlords now receive a basic-rate tax credit against their finance costs. In practice, this means the full rental income is counted when working out which tax band applies, and then a credit is applied at the basic rate afterwards. The consequence is that the relief a landlord receives is effectively capped at the basic rate, regardless of the tax band they actually fall into. For a basic-rate taxpayer, the impact may be relatively limited. For a higher-rate or additional-rate taxpayer, the effect can be substantial, because they no longer get relief at their marginal rate. It can even push some landlords into a higher tax band on paper, since gross rental income is now included in the calculation before the credit is applied. This is why two landlords buying the same property can end up with very different net returns depending on their personal tax position. When you use DealFlow AI to review a listing, the deal score and yield estimates give you a market-level view of the opportunity, which you can then combine with your own Section 24 position to understand what the deal genuinely returns to you after tax.

Who Section 24 Affects Most and Why It Matters for Your Deal

Section 24 does not affect every landlord equally, and understanding where you sit is essential before committing to a purchase. The landlords most affected tend to be higher-rate and additional-rate taxpayers who hold mortgaged buy-to-let properties in their own name. Because these investors previously enjoyed relief at their marginal rate, the shift to a basic-rate tax credit represents the biggest reduction in the value of their mortgage interest relief. Landlords with large mortgages relative to their rental income also feel the change more keenly, since finance costs make up a larger share of their outgoings. By contrast, landlords who own property outright with no mortgage are largely unaffected by Section 24, because there is no finance cost to account for in the first place. Basic-rate taxpayers may notice a smaller impact, although they should still be mindful that including full rental income in the tax calculation can, in some cases, tip them closer to the higher-rate threshold. Many investors have responded to Section 24 by exploring incorporation, holding properties through a limited company where different tax rules can apply, though this route carries its own costs, complexity and considerations that only a qualified professional can properly assess for your situation. Why does this matter when hunting for deals? Because the headline yield on a listing tells only part of the story. A property showing a strong gross yield above the commonly cited 6 percent benchmark can still deliver a modest net return once Section 24 and your personal tax band are applied. DealFlow AI helps you avoid falling for surface-level numbers by analysing Rightmove and Zoopla listings and returning rental yield estimates and investment verdicts. You get a consistent, data-informed starting point, then apply your own tax position to see whether the deal truly works for you specifically.

How to Factor Section 24 Into Your Investment Decisions

Building Section 24 into your investment process starts with being honest about your own tax position and modelling returns on a net rather than gross basis. Too many landlords focus only on gross rental yield, but the figure that actually reaches your pocket depends on your tax band, your mortgage interest costs, void periods, maintenance, insurance, letting fees and other running costs. A disciplined approach is to begin with the market fundamentals of a property, then layer your personal circumstances on top. Start by establishing the likely rental income and the purchase price to understand the gross yield, keeping the widely used 6 percent gross yield benchmark in mind as a rough sense check rather than a guarantee. From there, estimate your finance costs and remember that under Section 24 you can no longer simply deduct the full interest, only claim a basic-rate credit against it. Consider whether including the gross rent in your income might affect your tax band. Factor in the additional-property stamp duty surcharge on the purchase, which increases your upfront costs, and check the property's EPC rating given the minimum EPC E requirement for lettings. Then work through your expected running costs to arrive at a realistic net figure. This is where DealFlow AI fits naturally into your workflow. Rather than manually pulling numbers from each listing, you can use DealFlow AI to analyse Rightmove and Zoopla properties and quickly receive deal scores and rental yield estimates. This gives you a fast, repeatable way to filter opportunities and shortlist the properties worth deeper analysis. You then apply your Section 24 and tax modelling to the shortlist, ideally alongside advice from a qualified accountant. The combination of automated market analysis and careful personal tax planning tends to produce more resilient decisions than relying on headline yields alone, helping you avoid deals that look strong but underperform after tax.

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