Buy to Let Calculator UK

How This Calculator Works

The calculator works by taking your property and financial information and applying the relevant tax rules and rates for 2026/27. It calculates your gross rental yield, net rental yield, and total return on investment, including both income and capital growth.

For the stamp duty calculation, the calculator applies the additional property surcharge of 5% on top of standard SDLT rates. This surcharge increased from 3% to 5% in the Autumn Budget on 30 October 2024 and applies to all additional residential property purchases of £40,000 or more.

For income tax, the calculator applies the current tax bands and rates for 2026/27. Rental profits are calculated after deducting allowable expenses. Mortgage interest is not deducted from rental profits; instead, a 20% basic rate tax reduction is applied to finance costs. This is known as the finance cost restriction and applies to individual landlords.

The calculator is designed primarily for individual landlords (sole traders or individuals who own property in their own name). If you are considering purchasing a buy to let property through a limited company, the tax treatment differs significantly. Company landlords can deduct mortgage interest as an expense and pay corporation tax rather than income tax. This calculator does not currently support limited company calculations, but we are working on a separate version for corporate landlords.

For capital gains tax, the calculator applies the current rates of 18% for basic rate taxpayers and 24% for higher and additional rate taxpayers on residential property disposals.

What the Calculator Results Mean

The calculator provides a comprehensive breakdown of your buy to let investment returns:

• Gross Rental Yield: Your annual rental income as a percentage of the property purchase price, before costs and taxes.
• Net Rental Yield: Your annual rental income after deducting allowable expenses, mortgage interest, and income tax, as a percentage of the purchase price. This is an after-tax yield based on the calculator's methodology. Definitions of net yield can vary across the property industry, so this figure should be used as an estimate rather than a definitive industry-standard metric.
• Total Investment Return: Your total return including both net rental income and capital growth, expressed as a percentage.
• Stamp Duty Liability: The SDLT due on purchase, including the 5% additional property surcharge.
• Income Tax on Rental Profits: The tax due on your rental income after allowable deductions and finance cost relief.
• Capital Gains Tax: The estimated CGT due when you sell the property.
• Net Profit: Your total profit after all costs and taxes.

Understanding each of these figures helps you assess whether a buy to let property meets your investment goals and budget. It also allows you to compare different properties and scenarios.

Example Calculation

Example 1: Basic Rate Taxpayer purchasing a buy to let property for £250,000 with a 75% mortgage at 5% interest, generating £15,000 annual rent.

• Purchase Price: £250,000
• Annual Rent: £15,000
• Gross Rental Yield: 6.0%
• Stamp Duty: £10,000 (5% on first £125,000, 7% on next £125,000)
• Mortgage Interest: £9,375 (75% LTV × 5%)
• Allowable Expenses: £2,000 (estimate for insurance, repairs, management)
• Net Rental Profit Before Tax: £15,000 - £2,000 = £13,000
• Income Tax at 20% (on £13,000): £2,600
• Finance Cost Relief at 20% (on £9,375): £1,875
• Net Tax Due: £2,600 - £1,875 = £725
• Net Annual Return: £15,000 - £9,375 - £2,000 - £725 = £2,900
• Net Rental Yield: 1.16%

Example 2: Higher Rate Taxpayer purchasing the same property but with a 40% tax rate.

• Net Rental Profit Before Tax: £15,000 - £2,000 = £13,000
• Income Tax at 40% (on £13,000): £5,200
• Finance Cost Relief at 20% (on £9,375): £1,875
• Net Tax Due: £5,200 - £1,875 = £3,325
• Net Annual Return: £15,000 - £9,375 - £2,000 - £3,325 = £300
• Net Rental Yield: 0.12%

Example 3: Limited Company Landlord (for comparison only)

If the same property were purchased through a limited company, the tax treatment would be different. The company would pay corporation tax on the rental profit after deducting mortgage interest as an expense. The illustrative rental profit would be £15,000 - £9,375 - £2,000 = £3,625. The applicable Corporation Tax rate depends on taxable profits, associated companies, and the Corporation Tax rules in force for the relevant accounting period. This illustrative example assumes a 19% rate for simplicity, giving corporation tax of £689 and a net return of £2,936. This is provided for illustrative purposes only and does not account for additional costs such as dividend tax or other company-specific factors. The actual Corporation Tax rate could be 19%, 25%, or subject to marginal relief depending on the company's circumstances.

The examples above illustrate how your tax position significantly affects your net returns. Higher rate taxpayers pay more income tax on rental profits and receive only basic rate relief on finance costs, which can reduce net yields substantially.

Understanding Stamp Duty on Buy to Let Properties

When you purchase a buy to let property or any additional residential property, you pay higher rates of stamp duty. Based on current legislation, the rates for additional properties in 2026/27 are:

The surcharge applies to purchases of £40,000 or more. If you are replacing your main residence, you may initially pay the additional property surcharge but can later claim a refund if you satisfy the statutory replacement conditions. To qualify, you must sell your previous main residence within 36 months of purchasing the new property. This is a complex area, and professional advice is recommended.

First-time buyers do not qualify for first-time buyer relief on buy to let purchases because the property is not their main residence. The additional property surcharge applies regardless of whether you are a first-time buyer.

Our Stamp Duty Calculator provides more detailed SDLT calculations for all buyer types.

Tax on Rental Income for Individual Landlords

Rental income from buy to let properties is subject to income tax. You pay tax on your net rental profit, which is your rental income minus allowable expenses. Since April 2020, mortgage interest has not been deducted when calculating taxable rental profits.

Allowable expenses include letting agent fees, insurance, repairs and maintenance, ground rent, service charges, and other costs incurred in renting out the property. Capital improvements are not allowable as expenses but may reduce your capital gains tax liability when you sell.

Finance cost relief replaces the old system of deducting mortgage interest from rental income. Under the current system, individual landlords receive a tax reduction of 20% of their finance costs, regardless of their marginal income tax rate. This means higher and additional rate taxpayers cannot claim relief at 40% or 45% on their mortgage interest, significantly increasing their tax bills compared to the previous system.

The income tax rates for 2026/27 are:

• Personal Allowance: £12,570 (0% tax)
• Basic Rate: 20% on income from £12,571 to £50,270
• Higher Rate: 40% on income from £50,271 to £125,140
• Additional Rate: 45% on income above £125,140

Your rental profits are added to your other income when calculating your tax liability. The calculator applies the finance cost restriction automatically, showing you the net tax due after the 20% basic rate tax reduction.

Our Income Tax Calculator can help you understand your overall tax position, and our Rental Income Tax Calculator provides more detailed rental tax calculations.

Capital Gains Tax When Selling

When you sell a buy to let property, you may be liable for capital gains tax on the profit you make. The gain is calculated as the sale price minus the purchase price, minus any costs of buying and selling, and minus any capital improvements you have made.

For residential property disposals, the capital gains tax rates for 2026/27 are:

• Basic Rate Taxpayers: 18% on gains within the basic rate band
• Higher and Additional Rate Taxpayers: 24% on gains above the basic rate band

The annual CGT exemption for individuals for 2026/27 is £3,000. This means you can make gains up to this amount each tax year without paying CGT. Married couples and civil partners each have their own allowance.

You must report and pay any CGT on residential property disposals within 60 days of completion. Our Capital Gains Tax Calculator provides detailed CGT calculations for property disposals.

Financing Your Buy to Let Investment

Most buy to let investors use a mortgage to finance their purchase. The interest rate, loan-to-value ratio, and type of mortgage you choose significantly affect your returns.

Buy to let mortgages typically require a deposit of at least 25% of the purchase price, although some lenders may accept 20% for certain properties. The interest rates are generally higher than residential mortgages. Many buy to let mortgages are interest-only, meaning you only pay the interest each month and the capital is repaid when you sell or refinance.

When calculating your returns, it is important to use realistic interest rates and account for potential interest rate changes. The calculator allows you to input your own mortgage details to get a more accurate picture.

For individual landlords, remember that mortgage interest receives basic rate tax relief (20%) rather than being deducted from rental profits. This means the effective cost of borrowing is higher for higher rate taxpayers, as they cannot claim tax relief at their marginal rate.

For limited company landlords, mortgage interest is fully deductible as an expense when calculating corporation tax. This can make company ownership more tax-efficient for higher rate taxpayers, although other factors such as dividend tax, corporation tax, and additional compliance costs should also be considered.

Understanding Rental Yields

Rental yields are a key metric for assessing the potential return from a buy to let property. The gross rental yield is your annual rental income divided by the property purchase price, expressed as a percentage. The net rental yield is your annual rental income after all costs and taxes, divided by the purchase price.

There is no single "good" yield that applies to all properties. Rental yields vary significantly depending on location, property type, tenant demand, and local market conditions. As illustrative market observations, yields in London and the South East are typically lower (3% to 5%) due to higher property prices, while yields in the North and Midlands are often higher (5% to 8%) but capital growth may be slower. These ranges are illustrative only and should not be treated as fixed expectations.

When comparing properties, focus on the net yield rather than the gross yield, as costs and taxes can significantly reduce your actual return. The calculator helps you understand both figures so you can make more informed comparisons.

Common Mistakes

Underestimating costs. Many investors focus on rental income and forget about the many costs involved, including mortgage interest, insurance, repairs, letting agent fees, ground rent, service charges, and void periods. You should budget at least 15-20% of rental income for these costs.

Ignoring the finance cost restriction. Individual landlords cannot deduct mortgage interest from rental profits. Instead, they receive a 20% basic rate tax reduction. Higher rate taxpayers should be particularly careful, as this significantly increases their tax bills compared to the old system.

Using the wrong SDLT rates. Buy to let purchases attract the 5% additional property surcharge. Using standard SDLT rates will significantly underestimate your purchase costs.

Forgetting about CGT. When you sell, you may have a significant capital gains tax bill. The annual exemption of £3,000 is relatively small, so most gains will be taxable.

Overlooking void periods. Properties are not always rented out continuously. You should factor in void periods and budget for periods with no rental income.

Comparing gross yields without considering tax. Two properties with the same gross yield can have very different net returns depending on your tax position, mortgage costs, and other expenses. Always use net yields for comparisons.

Our Rental Income Tax Calculator provides more detailed tax calculations for rental property investors.