Tax has a major effect on whether a buy-to-let makes money, and the rules for landlords have tightened in recent years. This guide explains buy-to-let and tax in plain English: how rental income is taxed, the restriction on mortgage interest relief, the stamp duty surcharge, and why many landlords consider a company structure.
Rental income is taxable
The rent you receive from a buy-to-let is taxable income, added to your other income and taxed at your marginal rate after allowable expenses. You declare it through self assessment, and you can deduct certain running costs, such as letting agent fees, maintenance, insurance and some others, before working out the taxable profit. Understanding what is taxable and what you can deduct is the starting point for a landlord's tax position.
The mortgage interest restriction
A major change for landlords is that individual landlords can no longer simply deduct mortgage interest as an expense. Instead, since changes that took full effect in April 2020, they receive a tax credit worth 20% of their finance costs, the basic rate. This means higher-rate and additional-rate taxpayers no longer get full relief on their mortgage interest, which significantly increases the tax on their rental profits compared with the old rules.
Why this matters for higher-rate taxpayers
For a higher-rate taxpayer, only getting a 20% credit rather than full relief effectively increases the tax cost of their mortgage interest, reducing their after-tax profit. This is why higher-rate taxpayers face stricter rental cover requirements, usually 145%, as our guide to the rental cover stress test explains, and why many higher-rate landlords now consider holding property through a company instead, where interest remains fully deductible.
Other allowable expenses
Beyond mortgage interest, landlords can deduct various running costs when working out taxable profit, including letting agent and management fees, repairs and maintenance (but not improvements), landlord insurance, ground rent and service charges, and certain other expenses. Keeping good records of income and allowable costs is important for an accurate tax return. Knowing what you can and cannot deduct helps you understand your real, after-tax return from a rental.
The stamp duty surcharge
When you buy a buy-to-let, you usually pay the additional-property stamp duty surcharge, currently 5% on top of the standard rates, on each band, as our guide to buy-to-let stamp duty explains. This adds a significant upfront cost to acquiring a rental property, so it must be factored into your investment sums alongside the deposit and other fees when judging whether a purchase stacks up.
Capital gains tax on sale
When you sell a buy-to-let for a profit, you may pay capital gains tax on the gain, unlike your own home, which usually qualifies for relief. There is an annual capital gains allowance, and the rate depends on your income and the gain. Planning for capital gains tax is part of considering the full return from a rental investment over its life, from purchase through to eventual sale.
The limited company route
Because of the interest relief restriction, many landlords, especially higher-rate taxpayers, now hold buy-to-lets through a limited company, where mortgage interest remains fully deductible and profits are taxed at corporation tax rates, as our guide to limited company buy-to-let explains. This is not automatically better, since it has its own costs and tax on extracting profits, so it needs careful, individual consideration.
Keeping good records
Because rental income and allowable expenses must be reported through self assessment, keeping accurate records is essential. Recording all rent received and every allowable cost, with receipts, makes completing your tax return easier and ensures you claim everything you are entitled to. Good record-keeping also helps if your return is ever queried. Treating your buy-to-let like the business it is, with proper records, is an important habit for landlords.
The property allowance
There is a small property allowance that means a limited amount of property income each year can be received tax-free without needing to report it, which can help those with very small rental incomes. For most landlords with a mortgaged buy-to-let, income exceeds this, so it has limited effect, but it is worth being aware of. The detail of allowances changes, so checking current rules or taking advice is sensible.
Joint ownership and tax
If you own a buy-to-let jointly, for example with a spouse, the rental profit is usually split between you and taxed on each owner separately, which can be tax-efficient if one owner pays a lower rate. The way ownership is structured can therefore affect the overall tax. Because the rules have conditions, particularly between spouses, this is an area where tax advice can help you arrange ownership sensibly.
Planning for the tax bill
Because tax on rental profit is paid through self assessment, often some months after the income is received, it is important to set money aside for it rather than spending all the rent. Planning for the tax bill, and any payments on account, avoids a shock when it falls due. Treating a portion of your rental profit as the taxman's from the outset helps you manage your buy-to-let finances smoothly.
Why tax advice matters
Landlord taxation is complex and has changed significantly, with the interest relief restriction, the surcharge and company considerations all in play. The right approach depends heavily on your income, plans and circumstances. Because mistakes can be costly and the rules intricate, taking advice from a qualified tax adviser is strongly recommended, as our guide to limited company buy-to-let notes. This guide is general information, not tax advice.
How tax shapes your real return
Tax has such a large effect that two landlords with identical properties can end up with very different profits depending on their tax band and structure. A basic-rate taxpayer keeps more of their rental profit than a higher-rate one, who loses more to the interest relief restriction. This is why working out your after-tax return, not just the headline rent, is essential to judging whether a buy-to-let is genuinely worthwhile for you.
Because the rules are detailed and shifting, and the right structure depends on your whole financial picture, building tax into your buy-to-let plans from the start, with professional advice, helps you avoid unpleasant surprises and make decisions, such as personal versus company ownership, on a sound footing.
In short, tax is one of the biggest factors in whether a buy-to-let succeeds, so it deserves attention from the very start rather than as an afterthought at the end of the tax year, and a good accountant who understands property is often worth their fee many times over.
In short
Rental income is taxable after allowable expenses, but individual landlords now get only a 20% tax credit on mortgage interest rather than full relief, which raises the tax for higher-rate taxpayers. Buy-to-let purchases attract the 5% stamp duty surcharge, and selling at a profit can mean capital gains tax. Many landlords consider a limited company structure as a result. Tax has a big impact, so specialist advice is wise.
Where to get help and next steps
Read our guides to limited company buy-to-let, buy-to-let mortgages explained, and buy-to-let stamp duty. This is general information, not tax, mortgage or financial advice; consider speaking to a qualified tax adviser.