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How much can I borrow on a buy to let?

Buy to let lenders cap the loan twice: by the value of the property and by the rent. This works out both and shows which one limits you.

Property
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Lender criteria
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Lenders use their own figure, often higher than the rate you pay. Five year fixes are sometimes tested at the pay rate.
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How this is calculated

The loan to value limit is the property value multiplied by the maximum loan to value.

The rental cover limit is the annual rent divided by the test rate and then by the cover required. With rent of £15,000 a year, a 5.5% test rate and 125% cover, the most the rent supports is £15,000 divided by 0.055 divided by 1.25, or £218,182.

The maximum loan is the lower of the two. If the rent is the limit, the calculator also shows the rent you would need to borrow the full loan to value.

Rates and assumptions used

Common rental cover, basic rate or company125%
Common rental cover, higher rate145%
Common test ratearound 5.5%, varies by lender

Statutory rates last checked July 2026. Source: HMRC and gov.uk.

Worked example

A £250,000 flat let at £1,250 a month. At 75% loan to value the limit is £187,500. Rental cover at 125% tested at 5.5% supports £15,000 / 0.055 / 1.25 = £218,182, so the loan to value is the limit and the maximum loan is £187,500. At 145% cover the rent supports only £188,088, so the two limits almost meet.

Common questions

Why do higher rate taxpayers face a higher test?

Because they get less tax relief on mortgage interest, so lenders want more rent behind each pound borrowed. Limited company borrowers are usually tested at 125% since the company deducts its interest as a cost.

Can I use a lower test rate?

Some lenders test five year fixed rates at the rate you actually pay rather than a stressed rate, which can raise the loan considerably. A broker will know which lenders do this at the time.

Does my own income matter?

Usually much less than for a residential mortgage, though many lenders set a minimum personal income. Some will top up a shortfall in rental cover from your income.

This is an estimate, not financial advice. The result is arithmetic based on the figures you entered and the published rates listed above. Tax on rental profit is not included. Lenders apply their own criteria and will reach different figures. For advice specific to you, speak to a qualified adviser or mortgage broker.
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