Buy-to-let has been one of the most popular forms of investment in the UK for decades. At its simplest, it means purchasing a property with the intention of renting it out to tenants rather than living in it yourself. However, a series of tax changes introduced since 2015 — including restrictions on mortgage interest relief, higher stamp duty, and tighter lending rules — have significantly altered the financial landscape for landlords. Understanding the costs, tax obligations, and risks is essential before committing capital.
What Is Buy-to-Let?
Buy-to-let refers to purchasing a residential property specifically to let it to tenants. The investor (landlord) earns rental income and may also benefit from capital appreciation over time. Buy-to-let properties require specialist mortgage products — you cannot use a standard residential mortgage to purchase a property you intend to rent out. The sector has become considerably more complex since 2015, when the government began introducing a series of tax and regulatory changes aimed at cooling the market and levelling the playing field between landlords and first-time buyers.
Buy-to-Let Mortgages
Buy-to-let mortgages differ from residential mortgages in several important ways. Lenders typically require a larger deposit — usually a minimum of 25%, though some specialist lenders may accept 20%. Interest rates are generally higher than on residential products, reflecting the additional risk lenders associate with rental properties.
Affordability is primarily assessed on the expected rental income rather than your personal income. Most lenders require the projected rent to cover 125% to 145% of the monthly mortgage payment at a stress-tested interest rate (often 5% to 5.5%, regardless of the actual rate charged). This stress test ensures there is a buffer if rates rise or the property sits empty between tenants.
Interest-only mortgages are common in buy-to-let. With an interest-only mortgage, you pay only the interest each month and repay the full capital at the end of the term — typically by selling the property. This keeps monthly costs lower and maximises cash flow, but it means you are relying on property values at least holding steady. Maximum borrower age limits vary by lender, with some lending up to age 75 or 80 at the end of the mortgage term.
Tax on Rental Income
Rental income is added to your other income and taxed at your marginal rate of income tax. You can deduct certain allowable expenses before calculating your tax liability, including letting agent fees, maintenance and repair costs, buildings insurance, ground rent, service charges, accountancy fees, and advertising costs for finding tenants.
One of the most significant changes for individual landlords was the phased introduction of Section 24 of the Finance (No.2) Act 2015. Previously, landlords could deduct mortgage interest payments as an expense before calculating their taxable profit. Since April 2020, this relief has been fully replaced by a basic rate (20%) tax credit. This means higher-rate and additional-rate taxpayers now pay substantially more tax on rental income than they did before the change.
Section 24 Impact: Higher-Rate Taxpayer Example
| Before Section 24 | After Section 24 | |
|---|---|---|
| Annual rent | £12,000 | £12,000 |
| Mortgage interest | £8,000 | £8,000 |
| Taxable profit | £4,000 | £12,000 |
| Tax at 40% | £1,600 | £4,800 |
| Less 20% tax credit on interest | N/A | −£1,600 |
| Tax payable | £1,600 | £3,200 |
Simplified example for illustration. In this scenario, the higher-rate taxpayer's tax bill doubles under Section 24 rules. The effect is even more pronounced for additional-rate (45%) taxpayers. Source: GOV.UK — Changes to tax relief for residential landlords
Stamp Duty Surcharge
Since April 2016, buyers purchasing additional residential properties (including buy-to-let) have paid a surcharge on top of the standard Stamp Duty Land Tax (SDLT) rates. This surcharge was originally 3% but was increased to 5% from 31 October 2024 as part of the Autumn Budget.
SDLT on a £250,000 Buy-to-Let Property
- Standard SDLT (main residence)
- £2,500
- SDLT with 5% surcharge (additional property)
- £15,000
Based on SDLT rates effective from 1 April 2025: 0% on first £125,000, 2% on £125,001–£250,000 for standard purchases. The 5% surcharge applies to each band for additional properties. Source: GOV.UK — Stamp Duty Land Tax rates
The surcharge applies to the entire purchase price, not just the amount above a threshold. It is a significant upfront cost that eats into returns, particularly on lower-value properties where rental yields are thinnest.
Capital Gains Tax on Sale
When you sell a buy-to-let property at a profit, you are liable for Capital Gains Tax (CGT). Residential property gains are taxed at 18% for basic-rate taxpayers and 24% for higher- and additional-rate taxpayers. The annual CGT exempt amount is £3,000 (2024/25), which can be set against your gain before tax is calculated.
Unlike your main home, buy-to-let properties do not qualify for Principal Private Residence Relief, so the full gain (minus allowable costs such as purchase costs, improvement works, and selling fees) is taxable. Since April 2020, you must report and pay CGT on UK residential property disposals within 60 days of the completion date, rather than waiting until your next Self Assessment return.
Rental Yields
Rental yield is the most common measure of buy-to-let returns. Gross yield is calculated as annual rental income divided by the property purchase price, multiplied by 100. For example, a property purchased for £200,000 generating £12,000 per year in rent has a gross yield of 6%. Net yield accounts for costs such as mortgage payments, insurance, maintenance, void periods, and management fees — and gives a more realistic picture of actual returns.
Approximate Gross Rental Yields by Region
- London
- 3% – 4%
- South East
- 3.5% – 5%
- North West
- 6% – 8%
- North East
- 7% – 9%
- Scotland
- 5% – 7%
- Wales
- 5% – 7%
Approximate ranges based on industry data. Actual yields vary significantly by area, property type, and condition. Higher-yielding areas often have lower capital growth, and vice versa — this is the classic yield vs capital growth trade-off.
Investors must decide whether they prioritise income (higher yields, typically in the North and Midlands) or capital growth (lower yields but stronger price appreciation, typically in London and the South East). Many experienced landlords aim for a balance of both.
Landlord Responsibilities
Being a landlord carries significant legal obligations. Failure to comply can result in fines, prosecution, or rent repayment orders. Key responsibilities include:
- Gas safety: An annual Gas Safety Certificate from a Gas Safe registered engineer is a legal requirement for all rented properties with gas appliances.
- Energy Performance Certificate (EPC): Rental properties must have a minimum EPC rating of E. Properties rated F or G cannot legally be let unless an exemption has been registered.
- Electrical safety: An Electrical Installation Condition Report (EICR) must be carried out by a qualified electrician every five years in England.
- Deposit protection: Tenancy deposits must be placed in a government-approved tenancy deposit scheme within 30 days of receipt.
- Right to rent checks: Landlords in England must verify that tenants have the legal right to rent in the UK before granting a tenancy.
- Smoke and CO alarms: Smoke alarms are required on every floor, and carbon monoxide alarms are required in rooms with a fixed combustion appliance (excluding gas cookers).
- HMO licensing: If the property is a House in Multiple Occupation (typically three or more tenants from two or more households), a mandatory HMO licence may be required. Some local authorities operate additional licensing schemes.
Incorporation: Buying Through a Limited Company
Since the Section 24 changes, an increasing number of landlords — particularly portfolio landlords and higher-rate taxpayers — have chosen to purchase buy-to-let properties through a limited company. The key advantage is that companies pay corporation tax (currently 25%) on profits rather than income tax (up to 45%), and mortgage interest remains fully deductible as a business expense for companies.
However, transferring existing personally-owned properties into a company is not straightforward. It is treated as a sale and a purchase, triggering CGT on any gain and SDLT on the market value of each property transferred — plus the 5% additional property surcharge. This makes incorporation most relevant for new purchases or for landlords building a portfolio from scratch. There are also additional compliance costs, including annual accounts, corporation tax returns, and potentially higher mortgage rates on company buy-to-let products.
Risks of Buy-to-Let
Buy-to-let is not a risk-free investment. Landlords should be aware of the following:
- Void periods: Periods without a tenant mean no rental income while costs continue. Budget for at least one month of voids per year.
- Problem tenants: Rent arrears, property damage, and the time and cost of legal proceedings for eviction are real risks.
- Interest rate rises: Higher rates increase mortgage costs and reduce net yields. Stress-test your figures at rates significantly above current levels.
- Regulatory changes: The Renters' Rights Bill proposes abolishing Section 21 "no-fault" evictions in England, introducing a new periodic tenancy model, and giving tenants greater rights. Further tax or regulatory changes remain possible.
- Illiquidity: Property cannot be sold quickly. A sale typically takes several months, and you may need to accept a lower price in a slow market.
- Maintenance costs: Boiler replacements, roof repairs, damp treatment — unexpected costs can wipe out months of rental income. Always maintain a cash reserve.
Alternatives to Direct Property Investment
For investors who want exposure to property without the responsibilities of being a landlord, there are several alternatives:
- Real Estate Investment Trusts (REITs): Listed companies that own and manage portfolios of property. Traded on stock exchanges, so you can buy and sell shares easily. REITs must distribute at least 90% of rental income as dividends. Can be held in an ISA or SIPP.
- Property funds: Open-ended or closed-ended funds that invest in commercial or residential property. Lower entry cost than buying a property directly, but some open-ended property funds have imposed dealing suspensions during market stress.
- Property crowdfunding: Platforms that allow you to invest smaller amounts (often from £100) into specific property developments or portfolios. More accessible, but these platforms are less established and carry additional counterparty risk.
These alternatives offer greater liquidity and lower entry costs than direct property ownership, but with less control over the individual assets held. Each carries its own risk profile, and investors should consider how property fits within their overall portfolio. A financial adviser can help assess which approach is most appropriate for your circumstances — see our guide on how to choose a financial adviser.
This guide is for general information only and does not constitute financial advice. The information is based on publicly available data from HMRC, GOV.UK, and other government sources. Tax rules, rates, and thresholds are subject to change — always check official sources for the latest values and seek professional advice before making investment decisions.