Buy-to-Let Mortgages: How They Work and What Lenders Look For
Updated: 05 April 2026
If you are buying a property to rent out, a buy-to-let mortgage is usually the starting point. Compared with residential lending, buy-to-let cases are assessed more heavily on the expected rent, the deposit, the property type, the borrower profile and the lender’s own risk appetite. Many buy-to-let mortgages are not regulated in the same way as residential mortgages, while consumer buy-to-let cases sit under a different framework. Mortgage rates, lender criteria, affordability rules and product availability can all vary by lender and can change.
Your home may be repossessed if you do not keep up repayments on a mortgage or any other debt secured on it.
What is a buy-to-let mortgage?
A buy-to-let mortgage is a mortgage for a property you intend to let to tenants rather than live in yourself. That could mean buying your first investment property, remortgaging an existing rental, moving a previously lived-in property onto a more suitable arrangement, or expanding an existing portfolio. If you are switching an existing property from residential use to rental, the right route may be consent to let or a remortgage, depending on your lender and your plans. If you are remortgaging an existing rental or reviewing your refinance options, see our remortgaging guide .
How buy-to-let differs from residential lending
Buy-to-let lending works differently from owner-occupied lending in a few key areas.
Deposit - Many buy-to-let cases are geared around a maximum of 75% loan-to-value, so a 25% deposit or equivalent equity is common, although exact limits vary.
Affordability - Lenders usually assess the expected rent against a stressed mortgage payment rather than relying only on salary multiples.
Repayment basis - Many buy-to-let mortgages are arranged on an interest-only basis, although capital repayment is also available.
Pricing and fees - Buy-to-let rates and fees are often different from standard residential products.
Property use - The way the property will be let matters. Standard single-let property, HMO, multi-unit property and holiday let cases can all sit in different parts of the market. If the property will be used for short-term holiday letting, read ourholiday let mortgage guide.
Who buy-to-let mortgages can suit
This page is written for:
first-time landlords
existing landlords buying again
borrowers remortgaging a let property
accidental landlords who need to regularise the mortgage position
landlords considering a limited company or SPV structure
portfolio landlords with several mortgaged properties
Some lenders are more comfortable where the applicant already owns their own home and has separate earned income outside the rent. Others are more flexible, but lender choice depends heavily on the detail of the case.
What lenders look at
When assessing a buy-to-let case, lenders usually look at the full picture rather than just the property value.
Deposit or equity position
Expected rental income
Personal income and overall affordability
Credit history and existing commitments
Property type and tenancy type
Landlord experience
Ownership structure, including personal name or limited company
Portfolio size if you already hold other mortgaged rentals
Some lenders also apply minimum income rules, and some prefer applicants who already own a residential property. Before applying, it is sensible to download your credit report and review any issues early.
Deposit, loan-to-value and borrowing
For many mainstream buy-to-let cases, the conversation starts around loan-to-value. A lower LTV can improve product choice and may help with pricing, while higher LTV cases can become narrower and more criteria-sensitive. Borrowing is then assessed against the projected or actual rent, not just against your income in the same way as a residential case.
In practical terms, the stronger the deposit, rent, credit profile and property type, the more options you are likely to have. That does not mean the cheapest headline rate is always the best fit. Fees, stress testing, early repayment charges, valuation approach and lender appetite all matter.
How lenders assess affordability
Buy-to-let affordability is usually assessed through rental coverage. The Prudential Regulation Authority expects firms to assess whether rental income is sufficient to support the interest cost, and the current industry standard minimum interest coverage ratio is stated as 125%, although firms may set higher thresholds. The PRA also expects interest rate stress testing, including a minimum borrower rate of 5.5% in certain cases, with special attention to portfolio landlords.
That is why two landlords buying similar properties can receive very different outcomes. The lender may treat taxpayer status, ownership structure, fixed rate length, portfolio size, property type and background commitments differently.
Interest-only or capital repayment
Many buy-to-let mortgages are interest-only, which keeps monthly payments lower because you are only paying the interest during the term. Capital repayment is also available and may suit some landlords who want to reduce the balance over time. The right structure depends on your cash flow, long-term plan and exit strategy. If you choose interest-only, you need a credible plan for repaying the capital at the end of the term.
Limited company buy-to-let
For some landlords, buying or remortgaging through a limited company can be worth exploring. In mortgage terms, this is a specialist area with different lender criteria, different documentation requirements and often different pricing from personal-name borrowing. Some lenders prefer a straightforward special purpose vehicle with a clean property-letting purpose. If you are considering this route, read our limited company buy-to-let guide.
Whether a limited company is the right route is not just a mortgage question. Tax treatment varies according to individual circumstances and is subject to change, so you should speak to a qualified accountant before deciding on the ownership structure.
Portfolio landlords and more complex cases
If you already have four or more distinct mortgaged buy-to-let properties in aggregate, lenders are likely to treat you as a portfolio landlord. At that point, underwriting becomes more detailed. The lender may want a full property schedule, current balances, rental figures, asset and liability information, portfolio cash flow and a clearer explanation of how the portfolio is managed. For deeper detail, see our portfolio landlord guide.
This is where broker-led packaging becomes much more valuable. A case can look strong on one property but still fail if the wider portfolio does not fit the lender’s model.
Costs and landlord responsibilities
The mortgage is only one part of the budget. Other costs can include valuation fees, legal costs, lender fees, broker fees where charged, insurance, repairs, furnishing, letting costs and contingency for void periods.
Stamp Duty Land Tax is also important. In England and Northern Ireland, purchases of additional residential property usually attract the higher SDLT rates, although the exact outcome depends on your circumstances. Use our stamp duty calculator for an initial estimate, then confirm the final figure with your solicitor.
You also need to understand the practical responsibilities of being a landlord. GOV.UK states that landlords must keep rented properties safe and free from health hazards, protect deposits where required, provide an EPC, ensure gas and electrical safety, and comply with other rules such as right to rent checks in England. HMO and local licensing rules can also apply depending on the property and area, so you should confirm the position with your local authority or solicitor.
Documents and application process
The exact paperwork varies by lender and by case type, but landlords are commonly asked for:
proof of identity and address
proof of income
bank statements
evidence of deposit or equity
current mortgage statement if remortgaging
expected rental assessment or tenancy evidence
details of other properties owned
company documents if buying through a limited company
For more detail on the wider mortgage process, see our mortgage application guide.
A typical process looks like this:
initial fact-find and lender research
decision in principle where appropriate
property and rental review
full application
valuation and underwriting
mortgage offer
conveyancing and completion
Speak to a buy-to-let mortgage broker
Whether you are buying your first rental, remortgaging an existing let property, reviewing a limited company structure or expanding a portfolio, the key is matching the case to lenders whose criteria fit the detail. Mortgage One can help you assess the options, structure the application properly and avoid wasting time with lenders that are unlikely to fit. Speak to our team.
The information provided in this article is for general guidance only and does not constitute personal or regulated financial advice. If you’d like to understand what these moves could mean for you, speak to Mortgage One. We can explain your options and timings based on your specific circumstances.
Some Buy to Let mortgages are not regulated by the Financial Conduct Authority.
FAQs
Can first-time landlords get a buy-to-let mortgage?
Yes. Some lenders will consider first-time landlords, although criteria can be tighter and lender choice may be narrower. Deposit size, personal income, credit profile, property type and whether you already own a home can all affect the options available.
How much deposit do I need for a buy-to-let mortgage?
Many buy-to-let cases are geared around up to 75% loan-to-value, which means a 25% deposit or equivalent equity is common. Some lenders and case types can differ, so the exact requirement depends on the lender, the property and your overall profile.
How do lenders assess buy-to-let affordability?
Lenders usually assess the expected rental income against a stressed mortgage payment using an interest coverage calculation. Some will also check your personal income, credit commitments and wider living costs.
Are buy-to-let mortgages interest-only or capital repayment?
Many buy-to-let mortgages are interest-only, but capital repayment options also exist. The right structure depends on your objectives, monthly budget and how you plan to repay the balance if you choose interest-only.
Can I get a buy-to-let mortgage through a limited company?
Yes, in principle. Many landlords use a limited company or special purpose vehicle, but lender criteria, documentation and personal guarantee requirements can differ. Mortgage advice and tax advice are separate, so you should also speak to a qualified accountant.
What is a portfolio landlord?
A portfolio landlord is generally a landlord with four or more distinct mortgaged buy-to-let properties in aggregate. Once a case falls into portfolio lending, the lender may assess the wider portfolio as well as the property being bought or remortgaged.
Do I pay higher Stamp Duty on a buy-to-let purchase?
Usually, purchases of additional residential property in England and Northern Ireland attract the higher Stamp Duty Land Tax rates, although the exact outcome can depend on your circumstances. Always confirm the final figure with your solicitor.
Are buy-to-let mortgages regulated?
Many buy-to-let mortgages are not regulated in the same way as residential mortgages. Consumer buy-to-let cases can sit under a different regulatory framework, so the position depends on why the property is being let and the circumstances of the case.