What is a buy-to-let mortgage?
A buy-to-let mortgage is a loan used to purchase a property you intend to rent out rather than live in, assessed primarily against the rental income the property can generate rather than your personal salary.
Deposits are typically higher than for residential mortgages, usually starting at 25%, and rates tend to be a little above equivalent residential deals to reflect the additional risk to lenders.
Most buy-to-let mortgages in the UK are interest-only, meaning monthly payments only cover the interest, with the capital repaid when the property is eventually sold or refinanced.
How do buy-to-let mortgages work?
Lenders calculate how much you can borrow largely from expected rental income, typically requiring the rent to cover 125-145% of the mortgage payment, calculated at a stress-tested interest rate.
Many lenders also check your personal income to confirm you can cover the mortgage if the property is empty between tenants, particularly for first-time landlords.
Here's a fictional example:
Meet Robert, buying his first rental flat
Robert wants to buy a £220,000 flat with a 25% deposit, needing a mortgage of £165,000.
The local rental market suggests around £950 a month, and the lender requires rental cover of 145% at a stressed rate of 6.5%, meaning the flat comfortably passes the affordability test.
He takes an interest-only buy-to-let mortgage at 5.4%, giving monthly payments of about £743, leaving a margin over his expected rental income to cover void periods and maintenance.
What types of buy-to-let mortgage are there?
Standard buy-to-let
For individual landlords buying in their personal name, assessed on rental income and often personal income too.
The most common route for someone buying their first or second rental property.
Limited company buy-to-let
The property is held within a limited company, which can offer tax advantages for higher-rate taxpayers.
Rates are often slightly higher and fewer lenders operate in this space, so a specialist broker helps.
Houses in multiple occupation (HMO)
For properties let room-by-room to multiple tenants, which can generate higher rental yields.
Requires specialist lending and often licensing from the local council.
Holiday let mortgage
For properties let short-term to holidaymakers rather than long-term tenants.
Assessed on seasonal rental projections rather than standard annual rent, with its own tax treatment.
Is buy-to-let right for me?
Buy-to-let tends to suit investors who:
- 1
Can absorb void periods
You need enough of a buffer to cover the mortgage if the property sits empty between tenants.
- 2
Understand landlord responsibilities
From safety certificates to deposit protection, being a landlord carries legal obligations.
- 3
Are investing for the medium to long term
Property is illiquid, so buy-to-let suits those not needing quick access to the capital.
What do I need for a buy-to-let mortgage?
Most UK lenders will require:
A deposit of at least 25%: Some lenders accept 20%, but rates and choice improve considerably above 25%.
Rental income covering the mortgage: Usually 125-145% of the monthly payment at a stressed interest rate, not just the pay rate.
A minimum personal income: Often £25,000 a year, particularly for first-time landlords, to show you can cover void periods.
A satisfactory credit history: As with residential mortgages, a clean file opens up better rates and more lenders.
Existing portfolio details: Landlords with four or more mortgaged properties are assessed under specific portfolio landlord rules.
How to compare buy-to-let mortgages
Look past the headline rate and check these five things:
- 1
Initial rate vs the follow-on rate
A cheap two-year fix can revert to a lender's standard variable rate of 7% or more once it ends, so know the exit point before you sign.
- 2
Fees, not just the rate
A lower rate with a £1,999 product fee can cost more overall than a slightly higher fee-free deal, especially on smaller loans.
- 3
Overall cost over the deal period
Compare the true cost of the initial period — rate, fees and any cashback combined — rather than the rate in isolation.
- 4
Early repayment charges
Fixed and tracker deals typically lock you in with charges of 1-5% of the balance if you remortgage or overpay heavily before the term ends.
- 5
Flexibility
Look for free overpayment allowances (usually 10% a year), porting rights if you move home, and payment holiday options.
Buy-to-let pros and cons
Pros
- Rental income can cover the mortgage and generate profit
- Property can grow in value over the medium to long term
- Interest-only options keep monthly outgoings lower
- A tangible asset compared with some other investments
Cons
- Deposits are higher than for residential mortgages
- Mortgage interest relief is now limited to a basic-rate tax credit
- Void periods and maintenance costs eat into returns
- Selling a property is slower than exiting other investments
Buy-to-let as an individual or through a limited company?
Buying personally is simpler and has lower setup costs, and can suit basic-rate taxpayers or those with just one or two properties.
A limited company structure can be more tax-efficient for higher-rate taxpayers, since mortgage interest is deducted before profit is taxed, but it comes with corporation tax, accountancy costs and fewer, pricier mortgage options.
The right structure depends on your tax position and how many properties you plan to hold, so it's worth taking specialist tax advice before you buy.
What happens if I can't keep up mortgage repayments?
Missing payments on a buy-to-let mortgage is reported to credit reference agencies and can ultimately put your home at risk, since the property is used as security for the loan.
Contact your lender as soon as you think you'll struggle. Under FCA rules, lenders must treat customers in financial difficulty fairly and can often offer a temporary reduced payment, a term extension or a short payment holiday.
Free, independent guidance is available from MoneyHelper and Citizens Advice, and speaking to your lender early keeps far more options on the table than waiting until arrears build up.
What are the alternatives to buy-to-let?
If direct property investment isn't right for you, consider:
Real Estate Investment Trusts (REITs)
Gives exposure to property markets through the stock market, without the hassle of being a landlord.
Property crowdfunding platforms
Pool money with other investors into specific developments or portfolios, with lower minimums than buying outright.
Holiday let ownership
Can generate higher yields than long-term letting in the right location, with different tax treatment worth checking carefully.
FAQs
About this guide
Written and reviewed by the Grow Your Business team, and kept up to date as rates, rules and provider terms change.
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