A buy-to-let mortgage is a mortgage designed for a property you intend to let to tenants. The broad idea is simple, but the underwriting is not. Lenders care less about whether you can just about afford the payment from salary, and more about whether the rent covers the debt under their stress test.
That is why buy-to-let borrowing feels different from a normal residential purchase. Deposits are larger, rates can be higher, and the lender will usually assess the deal as an investment as much as a home loan.
What is a buy-to-let mortgage?
A buy-to-let mortgage is a loan used to buy or remortgage a property that will be rented out. You are not meant to live in it yourself. If you want to move out of your home and rent it instead, you normally need either consent to let from your current lender or a formal remortgage onto a buy-to-let product.
Mainstream lender guides such as Lloyds, Halifax and RBS all frame the product in broadly the same way: it is lending for an investment property, with stronger reliance on rental income and higher risk controls than standard owner-occupier lending.
How it differs from a residential mortgage
| Feature | Residential mortgage | Buy-to-let mortgage |
|---|---|---|
| Main purpose | You live in the property | You rent the property out |
| Typical deposit | Often lower | Often 25% or more |
| Main affordability test | Personal income and outgoings | Rental income plus personal profile |
| Common repayment style | Repayment | Often interest-only |
| Regulation | Usually FCA-regulated | Often unregulated if not let to family |
Important: If you rent out a property on a residential mortgage without permission, you can breach your mortgage conditions. That is a lender issue first, not a technicality to ignore.
How buy-to-let mortgages work in practice
Most buy-to-let mortgages are still arranged on an interest-only basis. That means your monthly payment covers interest, not the capital balance itself. At the end of the term, you still owe the original loan amount.
That structure can make the monthly cash flow easier to manage, which is one reason it remains common among landlords. But it also means you need a realistic exit route, such as sale, refinance or separate capital repayment planning.
Interest-only vs repayment
| Option | What you pay monthly | Main advantage | Main drawback |
|---|---|---|---|
| Interest-only | Interest only | Lower monthly payments | Capital still outstanding at the end |
| Repayment | Interest plus capital | Debt reduces over time | Higher monthly cost, tighter cash flow |
For many landlords, the question is not which option is morally better. It is whether the rent still works once repairs, voids, agent fees, tax and mortgage costs are all included.
Did you know? Some lenders assess the same property very differently depending on whether you choose a 2-year fix, a 5-year fix, personal ownership or limited company borrowing. The structure changes the numbers.
How much deposit do you need?
In the UK market, 25% is the normal starting point. Some lenders will want more, especially for flats above shops, ex-local authority stock, HMOs, short leases, unusual construction or weaker rental cover.
A lower loan-to-value can also improve pricing. HSBC’s public buy-to-let rates page, for example, highlights the usual market logic: lower LTV often means better rates.
Typical deposit expectations
- 20% can be available in narrower parts of the market
- 25% is the standard benchmark many landlords work from
- 30% to 40% is common on more specialist or higher-risk cases
The real answer depends on the lender, the property and the rent.
How lenders decide how much you can borrow
The central test is usually rental cover. A lender wants the expected rent to exceed the mortgage payment by a buffer, often expressed as a percentage.
You will often see thresholds such as 125% or 145% of stressed mortgage interest, depending on the product and borrower type. Public lender criteria also show that some lenders distinguish between small portfolio and larger portfolio landlords, or between personal and limited company borrowing.
What lenders usually look at
- Expected monthly rent
- Loan-to-value
- Your credit profile
- Property type and condition
- Whether you are a first-time landlord
- How many mortgaged rental properties you already own
- Whether the purchase is personal or through a limited company
Attention: A property can look profitable on a letting portal and still fail a lender stress test. The underwriting model is not the same thing as your own cash flow projection.
Personal name or limited company?
This is one of the biggest strategic decisions. A mortgage in your own name may be simpler and sometimes cheaper. A limited company structure can help on tax, especially where you want to retain profits or where mortgage interest treatment matters.
But a company route brings extra admin, separate accounts, Companies House filings and lender-specific rules. Many limited company lenders really mean SPV buy-to-let, not a general trading company.
If you are weighing the structure rather than just the mortgage, read Sole Trader vs Limited Company for Landlords, Limited Company Buy-to-Let and SPV Buy-to-Let Explained.
What costs should landlords budget for?
The rate is only part of the picture. A buy-to-let deal can fail because the wider carrying costs were too optimistic.
Costs to model before you apply
- Deposit
- Arrangement fee
- Valuation fee
- Broker fee, if used
- Legal fees
- Stamp Duty on Buy-to-Let
- Insurance
- Letting agent fees
- Repairs and maintenance
- Void periods
- Tax on rental profit
A lot of first-time landlords focus on the monthly mortgage payment and ignore the rest. That is usually where the bad surprises come from.
Who can get a buy-to-let mortgage?
There is no single market-wide rule, but common themes do show up repeatedly in lender criteria.
Typical borrower profile
| Criteria area | What lenders often prefer |
|---|---|
| Age | Adult borrower, often with upper-age limits at term end |
| Minimum income | Sometimes required, even when rent is strong |
| Experience | First-time landlords accepted by some, not all |
| Portfolio size | Extra checks for portfolio landlords |
| Property value | Minimum thresholds often apply |
| EPC | Property must meet current legal minimums |
Some lenders are comfortable with first-time landlords. Others prefer experienced borrowers or broker-introduced business only.
How to prepare for a buy-to-let mortgage application
A good application is mostly about reducing uncertainty.
Before you apply
- Decide whether the property will be owned personally or through a company.
- Estimate realistic rent, not best-case rent.
- Run the deal with higher mortgage costs and a void assumption.
- Check the property is mortgageable and legally lettable.
- Gather ID, income evidence, portfolio details and deposit proof.
- Speak to a broker if the case is anything other than standard.
Cases where a broker usually helps
- Limited company borrowing
- Portfolio landlord cases
- HMOs or mixed-use properties
- Foreign income or non-standard employment
- Credit blips
- Transfers from personal ownership into a company
Is buy-to-let still worth it in 2026?
It can be, but only if the property still works after stress testing. Higher borrowing costs, tighter regulation and tax changes mean thin-margin deals break faster than they used to.
That does not mean buy-to-let is dead. It means lazy underwriting is dead.
| Reader type | Likely best next step |
|---|---|
| First-time landlord | Focus on deposit size, stress test and total costs before chasing yield |
| Higher-rate taxpayer | Compare personal ownership with limited company/SPV routes early |
| Existing landlord refinancing | Review rental cover against current lender stress tests before your fixed rate ends |
| Portfolio builder | Use a broker and model tax, admin and financing together, not separately |
Final verdict
A buy-to-let mortgage is not just a residential mortgage with a tenant attached. It is a different lending category with different logic. The deal needs to work for you and for the lender’s stress model.
If you are choosing your first route in, keep the decision simple: buy a mortgageable property, leave margin for repairs and voids, and do not let a broker illustration substitute for proper cash-flow planning.
If you are already thinking about company structures, mortgage interest restriction and reinvestment, the mortgage decision should sit inside a wider tax and ownership strategy, not outside it.
FAQ
Are buy-to-let mortgages regulated in the UK?
Often not, but some are. A buy-to-let mortgage may be regulated if it is a consumer buy-to-let case, for example where the circumstances are closer to an accidental landlord situation than a business-style investment.
Can you live in a buy-to-let property yourself?
Not without changing the arrangement properly. If you want to live there, speak to the lender first. The mortgage was underwritten on the basis that the property would be let.
What rental income do lenders usually want?
There is no universal figure, but many lenders want the expected rent to cover the stressed mortgage payment by a set margin, often 125% or more.
Do limited company buy-to-let mortgages require an SPV?
Very often, yes. Many lenders want a clean property-holding company with suitable SIC codes rather than a wider trading company.
What should I read next?
The most useful next pages are Limited Company Buy-to-Let, SPV Buy-to-Let Explained and Stamp Duty on Buy-to-Let.
This article is for general information only and does not constitute tax or financial advice. For guidance specific to your circumstances, consult a qualified accountant or tax adviser.
