Rental Yield Explained: How to Judge a UK Buy-to-Let Investment

Gross yield vs net yield

Gross rental yield is annual rent divided by the purchase price, expressed as a percentage. A property at £180,000 generating £900 a month gives a gross yield of 6 percent. It is a useful first filter when comparing markets, but it ignores costs.

Net rental yield deducts running costs — mortgage interest, management fees, insurance, maintenance, ground rent or service charge, void periods and an annual sinking fund — before dividing by the price (or sometimes by your cash invested). Net yield is what tells you whether a property actually pays its way after the bills.

ROI and cash-on-cash returns

Return on Investment for a leveraged buy-to-let usually focuses on cash-on-cash return — annual net cashflow divided by the cash you actually put in (deposit, SDLT, refurb, fees). With a typical 25 percent deposit and a healthy yield, well-bought UK BTLs can return 5 to 10 percent cash-on-cash before any capital growth.

Capital growth is the second engine. Over a 10-year hold, modest annual price growth combined with rental income can produce double-digit total annual returns — but it can also disappoint badly in a stagnant market. Always model both yield and price scenarios before committing.

Stress tests and lending criteria

Buy-to-let mortgage lenders apply Interest Cover Ratio (ICR) tests, requiring rent to cover the mortgage interest by 125 to 145 percent at a stressed rate. For higher-rate taxpayers, the typical requirement is 145 percent at a notional rate of 5.5 to 7 percent depending on lender and product term. Five-year fixed-rate products often have lower stress thresholds than 2-year fixes.

If a property barely passes ICR at today's rates, it is fragile. Build in headroom and avoid relying on aggressive rent assumptions to make the numbers work.

Section 24 and the limited company question

Section 24 has fully eliminated mortgage interest as a deductible expense for individual landlords; instead, a 20 percent tax credit is given. For higher-rate and additional-rate taxpayers this can dramatically reduce post-tax cashflow on highly geared properties.

A growing number of new buy-to-let purchases are now made through SPV limited companies. Companies pay corporation tax on profits and can deduct full mortgage interest. The trade-off is more complex accounts, slightly higher mortgage rates and personal tax on dividends or salary drawn from the company. Take advice — there is no universally right answer.

Voids, maintenance and the realistic numbers

Always model at least 1 month of void per year, even in strong markets. Build in 1 to 1.5 percent of property value annually for maintenance and an extra capex line for boilers, kitchens and bathrooms every 10 to 15 years. If you use letting agents, full management is typically 10 to 15 percent of rent plus VAT, plus tenant find fees.

Properties that pencil at headline 8 to 10 percent gross yield often net out at 4 to 6 percent once realistic costs and tax are applied. That can still be a good investment — but it should be compared honestly against alternatives such as listed REITs, index funds and pension contributions before locking up capital.

Frequently asked questions