Getting a buy-to-let mortgage requires a larger deposit than a standard residential mortgage, typically at least 25% of the property’s value, and lenders will assess the expected rental income rather than just your personal salary. The process shares some steps with a regular mortgage application but has distinct eligibility rules, tax implications, and affordability tests you need to understand before you start.
How Buy-to-Let Mortgages Differ
A buy-to-let mortgage is specifically designed for properties you intend to rent out rather than live in. You cannot use a standard residential mortgage for a rental property, and doing so would breach your mortgage terms. The key differences come down to three things: the deposit is bigger, the affordability assessment focuses on rental income instead of your salary, and the interest rates tend to be slightly higher.
Most buy-to-let mortgages are interest-only, meaning your monthly payments cover just the interest on the loan. You repay the capital at the end of the term, usually by selling the property. This keeps monthly costs lower, which helps the rental income cover the mortgage payments with room to spare.
Deposit and Loan-to-Value Requirements
Most lenders require a minimum deposit of 25% of the property’s purchase price, giving you a maximum loan-to-value (LTV) ratio of 75%. Some lenders ask for as much as 40%, particularly for higher-risk borrowers or less standard property types. A handful may accept slightly less than 25% in specific circumstances, but these deals are uncommon.
The size of your deposit directly affects the interest rate you’ll be offered. A 25% deposit unlocks most of the market, but putting down 30% or 40% can noticeably reduce your rate. If you’re stretching to meet the minimum, expect to pay more each month in interest compared to someone with a larger equity stake.
How Lenders Assess Affordability
Instead of calculating how much you earn from employment, buy-to-let lenders focus on the expected rental income from the property. They use something called the Interest Cover Ratio (ICR), which measures whether the rent comfortably exceeds the mortgage payments.
Lenders typically require the rental income to be at least 125% of the mortgage interest payments. So if your monthly mortgage interest would be £800, the property needs to generate at least £1,000 per month in rent. For higher-rate taxpayers, most lenders apply a stricter threshold of around 145%, because tax relief on mortgage interest is less generous at higher tax bands.
On top of this, lenders don’t use the actual interest rate on your mortgage for this calculation. They apply a “stress test” using a higher hypothetical rate to check that the numbers still work if interest rates rise. The Prudential Regulation Authority expects lenders to factor in likely future rate increases, so even if your deal has a low initial rate, the affordability check will use a higher figure.
Your personal income still matters to some degree. Many lenders require a minimum personal income (often £25,000 per year) regardless of the rental yield, and some will want to see that you already own your own home.
Documents You’ll Need
The paperwork for a buy-to-let application is similar to a residential mortgage but with a few additions. Expect to provide:
- Proof of identity and address: passport or driving licence, plus recent utility bills or bank statements showing your current address.
- Proof of income: your last two to three months of payslips and your most recent tax returns if you’re self-employed. If you already earn rental income from other properties, bring evidence of that too.
- Bank and savings statements: typically the last three months, covering current accounts, savings, and any investment accounts where your deposit funds are held.
- Proof of deposit: lenders will want to see where the money is coming from, especially if it involves a gift or the sale of another asset.
- Property details: the estate agent listing, the expected rental valuation (often provided by a letting agent), and the ratified sales contract once you have one.
- Existing mortgage statements: if you own other properties, lenders will want details of those commitments.
Self-employed applicants should have two to three years of accounts or SA302 tax calculation forms ready. Lenders scrutinise self-employment income more closely, so the more complete your records, the smoother the process.
Personal Name or Limited Company
You can buy a rental property in your own name or through a limited company, and the choice affects both your mortgage options and your tax position.
Buying in your personal name is simpler. More lenders offer buy-to-let mortgages to individuals, which means more competition and generally better rates. The downside is tax: since April 2020, individual landlords can no longer deduct mortgage interest from rental income before calculating tax. Instead, you receive a 20% tax credit on the interest paid. If you’re a higher-rate or additional-rate taxpayer, this significantly increases your tax bill compared to the old system.
Buying through a limited company, usually a Special Purpose Vehicle (SPV) set up specifically to hold property, allows the company to deduct mortgage interest as a business expense before paying corporation tax. This can be more tax-efficient for higher-rate taxpayers. However, fewer lenders serve this market, and the deals available often come with higher interest rates and arrangement fees. You’ll also face additional costs for company accounts, corporation tax filings, and potentially higher accountancy bills.
For a first buy-to-let property where you’re a basic-rate taxpayer, buying in your own name is usually the more straightforward option. If you plan to build a portfolio or you’re already in a higher tax band, running the numbers through a limited company structure is worth doing before you commit.
Stamp Duty on Buy-to-Let Purchases
Buy-to-let properties attract higher rates of Stamp Duty Land Tax (SDLT) because they count as additional residential properties. From 1 April 2025, the rates on additional properties are:
- Up to £125,000: 5%
- £125,001 to £250,000: 7%
- £250,001 to £925,000: 10%
- £925,001 to £1.5 million: 15%
- Above £1.5 million: 17%
These are significantly higher than the standard residential rates. On a £200,000 buy-to-let purchase, for example, the stamp duty would be £11,500 (5% on the first £125,000 plus 7% on the remaining £75,000). Non-UK residents pay an additional 2% surcharge on top of these rates.
The higher rates apply whenever you’ll own more than one residential property worth £40,000 or more after the purchase completes. Mixed-use properties (such as a shop with a flat above) are assessed under different, often lower, non-residential rates.
Steps to Getting Your Mortgage
The process from first enquiry to completion typically takes 8 to 12 weeks, though it can stretch longer if there are complications with the property chain or valuation.
1. Research Your Rental Yield
Before approaching any lender, work out the likely rental income for the area and property type you’re considering. Check listings on property portals and speak to local letting agents. The rent needs to clear the 125% (or 145%) ICR threshold against your likely mortgage payments, so knowing this figure early tells you whether the deal is viable.
2. Get an Agreement in Principle
An Agreement in Principle (AIP) is a conditional indication from a lender that they’d be willing to lend you a certain amount. It’s based on basic information about your income, the property value, and the expected rent. An AIP isn’t a guarantee, but it shows estate agents and sellers that you’re a serious buyer. Most lenders can issue one within a few days, sometimes within hours.
3. Find a Property and Make an Offer
With your AIP in hand and your budget clear, you can make an offer on a property. Sellers and agents are more likely to accept your offer quickly if you can show a mortgage agreement in principle.
4. Submit Your Full Application
Once your offer is accepted, you submit the full mortgage application with all supporting documents. The lender will arrange a property valuation, which for buy-to-let often includes an assessment of the rental potential. Some lenders use desktop valuations while others send a surveyor in person.
5. Receive a Formal Offer
If the valuation is satisfactory and your documents check out, the lender issues a formal mortgage offer. Your solicitor will then handle the legal work: searches, title checks, and preparing contracts for exchange.
6. Exchange and Complete
You exchange contracts (at which point the purchase becomes legally binding), then complete on the agreed date. Your mortgage funds are released to the seller, and you pick up the keys.
Costs Beyond the Deposit
Budget for several upfront costs on top of your deposit. Arrangement fees on buy-to-let mortgages commonly range from £1,000 to £2,000, though some lenders fold this into the loan balance. You’ll pay for a property valuation (typically £150 to £1,500 depending on the property), solicitor or conveyancer fees (usually £800 to £1,500), and the stamp duty outlined above.
Once you own the property, ongoing costs include landlord insurance, letting agent fees if you use one (often 8% to 15% of monthly rent for full management), maintenance, and void periods where the property sits empty between tenants. Factoring these into your yield calculation before you buy prevents unpleasant surprises once you’re committed.