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Buy-to-let mortgage affordability – a guide for landlords

4-minute read

Couple speaking to mortgage advisor about a mortgage application
Conor Shilling

Conor Shilling

1 November 2023

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Over 50 per cent of existing landlords have a buy-to-let mortgage, according to research by Simply Business. And if you’re renting out a property for the first time, the chances of you needing a buy-to-let mortgage could be even higher.

Average buy-to-let mortgage interest rates have increased steadily in recent years. What does this mean for your chances of getting a mortgage for your rental property approved?

Read on to find out more about how buy-to-let mortgage affordability works, the requirements borrowers need to meet, plus how to pass buy-to-let mortgage affordability and stress tests.

Buy-to-let mortgage affordability – what do you need to know?

Before approving your mortgage application, buy-to-let lenders will assess your affordability.

This includes looking at how much rental income the property is likely to make, plus whether you could afford the mortgage repayments if the interest rate increased significantly.

Lenders tend to be stricter with affordability checks for buy-to-let borrowers as they view these applications to be higher risk.

In recent years, the Bank of England and buy-to-let lenders have tightened their affordability criteria. This, combined with higher average interest rates, could make it harder for landlords to get a buy-to-let mortgage.

Read more: How to get a buy-to-let mortgage: a simple guide

Explained: buy-to-let mortgage requirements

When it comes to getting a buy-to-let mortgage, each lender will have different requirements. Here are some of the most common criteria:

  • minimum age – most lenders will require you to be 18 or 21 years old, with some requiring a minimum age of 25
  • maximum age – some lenders will set a maximum borrower age of 70 or 75, while others have no limit
  • income requirements – you could be assessed based on your annual salary as well as your expected rental income
  • deposit – most lenders will require a deposit of around 25 per cent of the property’s value
  • stress and affordability tests – to pass these, you’ll need to make sure your rental income is a certain proportion of the monthly mortgage and that you could withstand a significant interest rate rise
  • credit score – a bad credit score could stop your application from getting approved

It’s also important to remember that a buy-to-let mortgage will only be approved for a property you’re not going to live in. Most lenders will approve buy-to-let applications from first-time buyers, but it’s worth checking before.

Buy-to-let mortgage affordability test

Affordability checks are done by lenders before approving a buy-to-let mortgage. They’re designed to make sure that the borrower is in a financial position to pay back their loan comfortably.

What is a mortgage affordability test?

One type of affordability test is known as the income cover ratio (ICR). This means you need to prove that the rental income generated by your property is equivalent to between 125 per cent and 145 per cent of the mortgage repayments.

For example, you’re buying a property for £310,000 with a 20 per cent deposit of £62,000. The lender is offering a mortgage with an interest rate of four per cent. This means your monthly repayments will be £827. Based on an affordability check of 125%, you’d need minimum monthly rental payments of £1,033.75 (£12,405 a year).

Lenders often test ICR based on the borrower’s income tax rate:

  • basic rate taxpayers are usually assessed at 125 per cent
  • higher rate taxpayers are usually assessed at 145 per cent
  • additional rate taxpayers could be assessed at higher than 145 per cent

The extra buffer is built into affordability checks to cover other landlord costs, such as maintenance, insurance, and void periods when the property is empty.

Read more: How to work out rental yield for your buy-to-let property

Buy-to-let mortgage affordability stress test

A stress test is designed to make sure that you can continue to pay your mortgage repayments if your interest rate increases significantly.

Stress tests have become more of an issue for borrowers and lenders after the Bank of England base interest rate gradually increased from 0.1 per cent in October 2021 to 5.25 per cent by September 2023.

In the past, stress tests were usually done at three per cent above the lender’s standard variable rate. However, as interest rates have increased significantly, some lenders have been assessing buy-to-let mortgage applications with stress tests up to eight per cent.

Using the example of a property being bought for £310,000 with a £62,000 deposit, monthly mortgage repayments would increase to £1,653 with an interest rate of eight per cent. As a result, the minimum rental income would need to increase to £2,066.55 a month to meet the 125 per cent ICR.

It’s important to note that different lenders apply different interest rates as part of their stress testing.

This article is intended as a guide only. Please get advice from a mortgage adviser or financial expert if you’re not sure of anything.

Is there a Bank of England mortgage affordability test?

Rules for stress testing buy-to-let mortgages are set by the Bank of England’s Prudential Regulation Authority (PRA).

In 2016, the PRA introduced new underwriting standards which require lenders to make sure borrowers can cope with:

  • an interest rate of 5.5 per cent
  • or the product interest rate plus two per cent (whichever figure is higher)

Since 2022, many average BTL rates have surpassed 5.5 per cent. This means a stress test of two per cent above the product price is likely to be used by most lenders.

However, it’s been reported that lenders are stress testing beyond the requirements to reduce risk, which is making it more difficult for buy-to-let borrowers to get their application approved.

FCA mortgage affordability for buy-to-let

The majority of buy-to-let lending isn’t regulated by the Financial Conduct Authority (FCA). However, if you’re applying for what’s known as a “consumer” BTL mortgage, aimed at accidental landlords or those renting to family members, this is regulated by the FCA in the same way as a residential mortgage.

Buy-to-let mortgage affordability calculator

A range of lenders and price comparison websites provide buy-to-let mortgage calculators to help you work out:

  • how much you could borrow based on your monthly rental income
  • monthly mortgage payments based on your deposit and interest rate

This information can give you an idea of whether you’ll pass affordability checks before starting your application. The results may suggest you need to increase your expected rental income or save more towards your deposit before applying for a buy-to-let mortgage.

You can get started using Habito’s buy-to-let mortgage calculator, and get more in-depth information using Barclays’ buy-to-let affordability checks.

Do you have any unanswered questions about buy-to-let mortgage affordability? Let us know in the comments below.

Useful guides for buy-to-let landlords

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Conor Shilling

Written by

Conor Shilling

Conor Shilling is a professional writer with over 10 years’ experience across the property, small business, and insurance sectors. A trained journalist, Conor’s previous experience includes writing for several leading online property trade publications. Conor has worked at Simply Business as a Copywriter for three years, specialising in the buy-to-let market, landlords, and small business finance.

We create this content for general information purposes and it should not be taken as advice. Always take professional advice. Read our full disclaimer

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