Guide · 9 February 2026
Buy-to-let stress tests in plain English
Rental cover ratios decide whether a lender will entertain your purchase. Here is how those numbers are usually read.
Buy-to-let lenders rarely look only at the purchase price. They apply a stress rate — often higher than the product’s actual pay rate — and ask whether the expected rent covers a set percentage of that stressed interest. If the rent falls short, the loan may be reduced or declined even when your personal income looks strong.
Portfolio landlords face extra layers: existing rental statements, voids history, and sometimes a higher interest cover requirement. Limited company applications add their own paperwork trail for accountants.
Before you commit to a viewing schedule, ask an adviser to run a stress test using today’s published criteria for two or three lenders. Criteria shift, so the result is a snapshot, not a promise — yet it stops you chasing properties that cannot clear the ratio.
Keep a maintenance and void buffer outside the deposit. A mortgage that “works on paper” still needs cash when a boiler fails between tenants.