A buy-to-let mortgage is not a residential mortgage with a different label. It is assessed differently, priced differently and, in most cases, not regulated in the same way. That is why a deal that looks affordable on a residential calculator can fail a buy-to-let affordability test.
This guide explains how lenders actually judge a first-time landlord in 2026: the deposit you will need, the rental-cover test that decides how much you can borrow, the income and property rules that narrow lender choice, and the upfront costs that catch buyers out. It is general information, not personal mortgage advice. Check your own numbers with a whole-of-market buy-to-let broker before you offer.
What a buy-to-let mortgage is
A buy-to-let mortgage is a loan to buy a property you intend to let to tenants, rather than live in yourself. Most are interest-only: you pay the interest each month and repay the capital at the end of the term, usually by selling the property or remortgaging. That keeps monthly payments lower than a repayment mortgage, but you do not own the property outright at the end unless you have a separate repayment plan.
Most buy-to-let lending for investment purposes is not regulated by the Financial Conduct Authority (FCA) in the way a residential mortgage is. The exception is consumer buy-to-let, which generally covers letting a former home you did not buy as an investment, or letting to a close family member. Those cases carry extra protections. If either applies to you, say so at the outset, because it changes which lenders and rules apply.
Note the distinction between a first-time landlord and a first-time buyer. A first-time landlord has not previously owned a let property, even if they already own the home they live in. A first-time buyer has never owned any property, and faces a much narrower set of lenders. Some specialists will consider a first-time buyer going straight into buy-to-let, usually with a larger deposit, but most high-street lenders want you to own your own home first.
How much deposit do you need?
For most lenders in 2026, the standard answer is 25% of the purchase price, or a maximum loan-to-value (LTV) of 75%. LTV is the loan as a percentage of the property's value: a £150,000 loan on a £200,000 property is 75% LTV, and the deposit is the other £50,000.
Some specialist lenders offer 80% LTV (a 20% deposit), and a very small number have offered up to 85%. Those products usually carry higher rates and fees and stricter criteria — and, crucially, they often fail the rental-cover test below, because a larger loan needs a higher rent to pass. A deposit of 35% to 40% usually secures the most competitive rates and makes affordability easier. It is not just about getting accepted; it is about getting accepted on terms that still leave cash flow after costs and tax.
On a £200,000 purchase, a 25% deposit is £50,000 with a £150,000 loan, while a 40% deposit is £80,000 with a £120,000 loan. Do not spend everything on the deposit. You still need stamp duty, legal fees, survey costs and a contingency fund for voids and repairs.
The test that decides how much you can borrow
Buy-to-let affordability is driven mainly by rent, not salary. Lenders apply an interest coverage ratio (ICR), sometimes called rental cover. The test asks: does the monthly rent cover the monthly mortgage interest, at a stressed interest rate, by a set multiple?
The stressed rate matters more than the rate you actually pay. Under Prudential Regulation Authority (PRA) expectations, lenders generally stress-test at a rate allowing for rises — commonly 5.5% over the first five years, or the pay rate plus two percentage points where the fix is shorter than five years, while a fix of five years or more can sometimes be tested at the pay rate itself. Individual lenders apply their own versions, so treat 5.5% as a common benchmark, not a universal rule.
The multiple also varies with tax status:
- Basic-rate taxpayers and limited companies are commonly tested at 125%: rent must be at least 1.25 times stressed monthly interest.
- Higher-rate and additional-rate taxpayers buying in their personal name are commonly tested at 145%, because their mortgage-interest relief is restricted under Section 24 (see the limited-company guide in this series).
On a £150,000 loan stressed at 5.5%, monthly stressed interest is £150,000 × 5.5% ÷ 12 = £687.50. The rent needed is £859.38 a month at 125% ICR and £996.88 at 145%. If the realistic market rent is £900, the basic-rate test passes and the higher-rate test fails — on the identical property, price and loan. That is why investors check the ICR before falling in love with a property, and why a broker will ask your tax band before quoting a maximum loan.
Income, credit, property and other criteria
Rent does most of the work, but lenders still check you:
Minimum personal income. Many lenders set a floor, often around £25,000 a year, although some have no minimum and rely mainly on rent. You can pass the rental test and still fail the income floor. Self-employed applicants should expect to show tax returns and accounts, usually for the last two years.
Home ownership. Most lenders want first-time landlords to already own their own home. If you rent your own home, expect a much shorter lender list and possibly a larger deposit requirement.
Age and term. Lenders set minimum and maximum ages at application and at the end of the term. On an interest-only loan, the term affects your exit plan and the lender's comfort with it, so check the maximum age at term end, not just at application.
Credit history. Adverse credit narrows the field to specialist lenders and usually raises the rate. Defaults, County Court Judgements and missed mortgage payments weigh far more heavily than a single missed phone bill. Avoid applying to several lenders at once: multiple hard searches and declined applications can themselves become a problem.
Property type and condition. Lenders are often stricter than buyers. Non-standard construction, flats above commercial premises, short leases, properties needing major works, and houses in multiple occupation (HMOs) all have their own criteria, and some high-street lenders will not lend on them at all. A property needing a full refurbishment before letting may need bridging finance first. On a flat, check the lease length before you offer: a short lease can affect both mortgageability and resale.
Interest-only, repayment, fixed or variable?
Most first-time landlords choose interest-only, and most lenders expect it. On a £150,000 loan at 5%, interest-only costs £625 a month, while a 25-year repayment mortgage on the same loan and rate costs roughly £877 a month. The trade-off is the end-of-term bill: the £150,000 is still owed on interest-only. Lenders will ask for your repayment strategy — sale, remortgage subject to criteria at the time, or repayment from other funds. Repayment mortgages cost more monthly but build equity and remove that cliff. Some landlords split the loan, part interest-only and part repayment.
Upfront costs beyond the deposit
Budget for all of these before you offer:
Stamp Duty Land Tax (SDLT). In England and Northern Ireland, a buy-to-let purchase is normally an additional residential property, so standard SDLT bands apply plus a 5% surcharge on every band. Standard bands are 0% up to £125,000, 2% on £125,001–£250,000, 5% on £250,001–£925,000, 10% on £925,001–£1,500,000 and 12% above that — so additional-property rates are 5%, 7%, 10%, 15% and 17%. On a £200,000 buy-to-let purchase that is £6,250 on the first £125,000 plus £5,250 on the remaining £75,000: £11,500 in total. Scotland uses Land and Buildings Transaction Tax with an Additional Dwelling Supplement, and Wales uses Land Transaction Tax with its own higher rates. Your conveyancer should confirm the figure for your circumstances.
Mortgage and professional fees. Buy-to-let product fees are typically higher than residential fees, and some products charge a percentage of the loan rather than a flat fee — so compare total cost over the fixed period, not just the headline rate. Add conveyancing, valuation or survey, and any broker fee. A basic lender valuation protects the lender, not you; a homebuyer or building survey is a separate decision, and on an older property it is often money well spent.
Letting and compliance costs. Letting-agent fees if you use one, landlord insurance, gas and electrical safety checks, an Energy Performance Certificate (EPC) if one is not in place, and immediate repairs before the first tenant moves in all come out of the same cash pot in the first months.
What changed for landlords in 2026
The Renters' Rights Act 2025 brought its first major changes into force in England on 1 May 2026: Section 21 "no-fault" evictions were abolished, assured shorthold tenancies converted to periodic assured tenancies, and possession now requires a ground under Section 8. Rent increases are limited to once a year through the Section 13 process, with at least two months' notice, and tenants can challenge an increase they consider above market rent. Rental bidding wars are banned and rent in advance is capped.
Pre-offer checklist and common mistakes
1. Prove the rent from at least two independent sources — letting agents with comparable lets, not just a portal asking rent. 2. Run the ICR yourself at the stressed rate and the multiple for your tax band. If it fails, the deal fails however attractive the yield looks. 3. Check your lender pool: own home, minimum income, property type. Find out who remains before spending on surveys and legal work. 4. Total the cash: deposit plus SDLT plus fees plus a reserve covering a void period and one major repair. If that leaves no reserve, the deal is too big. 5. Decide the ownership route — personal name or limited company — before you offer. Changing route after exchange is costly. 6. Use a whole-of-market broker. They see lenders that do not deal directly with the public and know which criteria have tightened this month.
The most expensive mistakes are buying on gross yield alone, without deducting management, voids, maintenance and compliance costs; assuming rent will never change and voids will never happen; taking the cheapest headline rate without checking fees, early repayment charges and the revert rate; and borrowing the maximum with no cash reserve, so one boiler failure or two-month void becomes a crisis.
Frequently asked questions
Can I get a buy-to-let mortgage if I have never been a landlord before?
Yes, provided you already own your own home and meet the lender's income, credit and rental-cover criteria. Choice is narrower than for experienced landlords, and some lenders ask for a larger deposit. A first-time buyer with no property at all faces a much smaller lender pool.
How much deposit do I need?
Budget for 25% as the standard minimum. Some specialists accept 20%, but rates and criteria are stricter and the rental-cover test often fails at higher loan sizes. A 35% to 40% deposit usually secures better rates.
Do I need a minimum income?
Many lenders require around £25,000 a year, but this varies and some have no minimum. The rental-cover test is usually the binding constraint; the income floor is an additional check.
Is a buy-to-let mortgage interest-only?
Most are, but repayment mortgages are available. Interest-only maximises monthly cash flow but leaves the full loan to repay at the end of the term, so you need a credible repayment plan.
Related reading
- Limited Company Buy-to-Let vs Personal Name: Which Is Better in 2026?
- How to Calculate Rental Yield: Gross vs Net (With UK Worked Examples)