UK homeowners spent an average of 21.3% of their gross income on mortgage payments in 2025 - the highest share since 2008. That single figure, drawn from UK Finance's "Loans Where We Live" report (published May 2026), tells you the affordability floor has dropped further than at any point in the post-financial-crisis era.
What UK Finance Found
The data shows a market under real pressure. One in five pounds of gross income going to a mortgage payment is a meaningful threshold. Cross it and the household budget for everything else - savings, maintenance, emergencies - starts to compress fast.
At local authority level the picture is even sharper. Borrowers in North Norfolk spent 25.7% of gross income on mortgage repayments in 2025, according to UK Finance. The London Borough of Hillingdon came second at 25.1%. Eight of the ten least affordable local authorities sit in the London commuter belt, including Luton (24.9%), Slough (24.8%) and Spelthorne (24.8%).
Scotland sits at the opposite end of the scale. Seven of the ten most affordable areas in the country are north of the border. The data shows a clear geographic divide: if you are servicing a mortgage in commuter-belt England, you are carrying a significantly heavier income burden than the national average suggests.
Total purchase activity rose despite this pressure. 723,000 house purchase mortgages were advanced in 2025, up 17% year-on-year, per UK Finance. Volume went up even as the cost of carrying that debt, relative to income, hit a 15-year high.
What This Means for BTL Investors
The 21.3% figure is more than a headline. It is a stress-test benchmark. If owner-occupiers in a given area are already at 25% of gross income, there is limited capacity to absorb further rate rises without defaults or forced sales. That is both a risk signal and, in time, a potential buying signal for investors with cash or low-leverage positions.
Run your own numbers against this benchmark. The Property Filter BTL stress test calculator lets you compare your own debt service ratio against current income thresholds - a useful sanity check before you commit to a refinance or a new acquisition.
BTL activity grew across all UK regions in 2025, but the yield gap between regions is wide. Scotland leads: gross rental yields above 9% are available in the highest-performing local authorities, per UK Finance. At the bottom, South Hams in Devon returned just 5% gross, with Cambridge (5.3%) and the Derbyshire Dales (5.3%) close behind.
Stamp duty surcharges, the phased removal of income tax relief on mortgage interest, and tighter underwriting standards have all raised the bar for BTL viability, UK Finance noted. Some landlords have already left the market as a result. The underlying picture is one of a leaner, more selective landlord base - which means less competition for the right deals in the right locations.
For a broader framework on how to position around these numbers, the Property Filter investment strategies guide covers the core approaches that hold up in a higher-rate environment.
The Wider Trend and What to Watch
Strip out the headline number and the year-on-year direction matters as much as the level. The data shows affordability has been tightening since rates began rising in 2022. The 21.3% figure for 2025 is not a one-off spike - it is the continuation of a trend that began when the Bank of England started its rate cycle.
The gap between the most and least affordable local authorities is now significant. North Norfolk borrowers spend around 4.4 percentage points more of their income than the UK average. That gap reflects both local house price levels and local income levels - and in some commuter-belt areas, both are moving against affordability at the same time.
London mortgage debt is also at a different scale. The typical London borrower carried £280,000 of mortgage debt in 2025 - nearly £70,000 more than the South East, the next highest region, per UK Finance. Northern Ireland had the lowest average at £99,500. These are not just different affordability ratios. They are different risk profiles.
For investors using leverage, the negotiation and finance resources at Property Filter cover how to position debt structure in markets where borrower strain is elevated. And the full calculator hub gives you the tools to model scenarios rather than rely on national averages that may not reflect your target market at all.
Key takeaways
UK homeowners spent 21.3% of gross income on mortgage payments in 2025, the highest share since 2008, per UK Finance.
Regional variation is extreme - from below 15% in parts of Scotland to above 25% in the London commuter belt; the national average conceals very different local risk profiles.
Consider focusing BTL acquisition activity on higher-yield, lower-affordability-pressure regions, and run your own debt service ratios against the 21.3% benchmark before refinancing or expanding.
