Standard Buy to Let Mortgages

A buy to let mortgage is designed for landlords purchasing or remortgaging a rental property. Instead of affordability being assessed on your salary alone, lenders look primarily at the expected rental income and apply rental stress testing to check the mortgage is sustainable. You’ll typically choose between interest-only buy to let mortgages (popular with investors who want lower monthly payments and to focus on yield), or repayment mortgages, which steadily reduce capital. Which is better? It depends on your strategy, tax position and exit plan, however most landlords choose interest-only.

​A buy to let is a bit like a small business - the rent is your turnover, the mortgage is your operating cost, and your net yield is the profit. Lenders want to see that the “business” runs with enough margin, even if mortgage rates rise. In some cases, short-term funding may be used before transitioning onto a buy to let mortgage once works or stabilisation are complete, particularly where investors are using a bridge-to-let or BRRR strategy to recycle capital.

Finance is only one part of successful property investment. Professional landlords must also adapt to changes in regulation, and our analysis of the Renters' Rights Act explores why these reforms may create long-term opportunities as well as challenges.

UK Buy to let mortgage rates move with wider funding costs, swap rates, lender appetite, and your specific loan profile. Expect pricing to vary by LTV, product type (fixed vs. tracker), term length, property type, and whether you’re applying in a limited company (SPV).

​Shorter fixes can offer flexibility, however 5-year fixed products often improve stress test results, because lenders may use a lower stress rate for longer fixes, enabling larger loans. Trackers align to base rate changes, which can be attractive if you anticipate cuts, but remember rent needs to cover the payment across cycles. Want an instant sense check? Try our buy to let mortgage calculator to compare scenarios.

Many investors use a dedicated SPV (Special Purpose Vehicle) for tax efficiency, ringfencing and long-term portfolio growth. Lenders assess SPV applications slightly differently, with rates and fees sometimes marginally higher, but stress testing can be more favourable in certain cases, particularly for higher-rate taxpayers.

An SPV is typically set up with standard SIC codes for property letting or management, and lenders generally prefer simple, clean structures rather than trading companies.

For a detailed comparison of SPV vs personal ownership, including tax considerations and lender criteria, see our limited company buy to let page.

Choosing interest-only buy to let reduces monthly payments and can lift your net yield. This is particularly common for investors operating a BRRR investment strategy, where long-term cash flow and refinance leverage are central to the approach. The trade-off is capital remains outstanding, so your exit relies on sale, future refinancing, or lump-sum repayment. Repayment mortgages steadily reduce debt and can be sensible for lower-yield assets or investors who value de-leveraging. How do you decide? Model both options using our buy to let mortgage calculator and assess cash flow, tax, and long-term goals. 

Lenders will take your prospective mortgage payment at a stressed rate (for example, a notional rate above today’s mortgage interest rates UK) and require rent to cover that by a set interest coverage ratio (ICR). For a higher-rate taxpayer, an ICR of 145% is common. For a 5-year fixed and/or an SPV purchase, some lenders use a lower stress rate or allow 125% ICR, resulting in greater borrowing headroom. This is why the best buy to let mortgage options can change with your tax band and product choice.

Take a property worth £400,000, with a 75% LTV mortgage (£300,000). If the mortgage rate were, for example, 3.75% an interest only mortgage payment would be £938 per month. If the mortgage were a 2-year fixed rate, the lender may require a stressed rate of 5.75%, resulting in a stressed payment of £1,438. If this property were bought in a personal name by a higher-rate tax payer, most lenders would require a 145% ICR, meaning that the stressed rent requirement would be £2,084! Buying the same property with the same LTV in an SPV (limited company) on a 5-year fixed rate, would usually result in a stressed rent requirement of £1,172 - a big difference and due to our stress testing rules are applied in different scenarios. 

Run your property through in our buy to let stress test calculator to avoid surprises and plan ahead.