Landlords with four or more mortgaged properties now face closer checks
Lenders assessing landlord borrowers have been required to look beyond the property being financed since the Prudential Regulation Authority set out its portfolio landlord underwriting framework in 2016, a requirement that has tightened further in recent years as landlord portfolios have grown more complex.
The PRA's Supervisory Statement SS13/16, published in September 2016, requires lenders to assess borrowers with four or more mortgaged buy-to-let properties, its definition of a portfolio landlord, against their whole portfolio rather than a single loan.
Specialist brokers say that requirement has become more forensic over the past two to three years, with underwriting now extending to a landlord's debt exposure, aggregate leverage, cash flow resilience and refinancing risk. Most lenders apply interest coverage ratio thresholds of between 125% and 145%, varying by tax status and borrower profile.
One lender's regional lens
Redwood Bank has put its own data behind that framework. New analysis from the bank, covering landlord investment patterns between 2021 and 2026, found that professional investors are becoming more concentrated in their home regions despite higher interest rates, regulatory reform and changing tenant demand.
"Assessing a landlord today isn't simply about looking at an individual property and a blanket portfolio check. It's about understanding the borrower's wider strategy, their experience and why a particular investment makes sense for their business," said Tom Worbey, senior product manager at Redwood Bank.
He said lending decisions need to keep pace as landlord portfolios continue to become more sophisticated and more targeted.
The value of local knowledge
Worbey said the buy-to-let market has changed considerably over the past five years. Professional landlords are now operating in a more complex environment that includes higher borrowing costs, increased regulation and rising expectations around property management.
He said local knowledge has become a genuine competitive advantage in this climate: "Experienced landlords understand the markets they operate in, they know what tenants are looking for, they have relationships with local agents and contractors and they're often better placed to identify opportunities that others might miss."
Redwood Bank's research found that landlords are placing more weight on operational expertise, local market knowledge and long-term investment quality in their buying decisions.
A map being redrawn
The East Midlands recorded the largest change in Redwood Bank's data, with local investment among landlords rising by 15.1% over the five-year period. The South West followed closely, posting a 14.2% increase in landlords buying within their own area.
Wales moved in the opposite direction, recording a 9.4% fall in local investment as landlords extended their portfolios into the neighbouring South West.
Separate research produced with specialist buy-to-let lender Foundation found landlords reported an average portfolio value of £1.8 million and gross yields of 6.4% in the second quarter of 2026, with 86% operating at a profit. Yields varied considerably by region, with the East of England and East Midlands topping the table at 7.3%, compared with 5.3% in Central London.
Lending data from Together points to a similar pattern across the wider market: the North West's share of its buy-to-let funding rose by 3.3 percentage points between 2020 and 2025, Scotland by 2 percentage points and Yorkshire and the Humber by 1.1 percentage points, while Greater London and the South East's share fell over the same period.
The same Foundation-backed research found that higher-yielding regions also carry greater operational risk. The North East recorded the highest proportion of landlords experiencing void periods at 55%, with rental arrears affecting 42%, while arrears were also elevated in Yorkshire and The Humber at 43%, the North West at 39% and the East Midlands at 37%, all above the UK average of 26%.
UK Finance's Q1 2026 figures offer a national comparison point. Buy-to-let mortgages in arrears greater than 2.5% of the outstanding balance stood at 8,960 at the end of the quarter, a fall of 24.3% over the year, with 810 possessions, unchanged year-on-year. Lending to portfolio landlords with four or more mortgaged properties rose 10.7% year-on-year to £3.2 billion over the same period.
Structure follows the tax rules
Redwood Bank's research covers a private rented sector that continues to professionalise. A growing number of investors now operate through multiple limited company special purpose vehicles, holding portfolios that combine buy-to-let, HMOs, mixed-use and commercial property.
Redwood Bank said many experienced investors are concentrating portfolios in locations where they already understand local planning and licensing requirements, tenant demand, rental values and property management networks, rather than diversifying geographically for its own sake. The bank said this is particularly relevant for HMO investors, given how licensing rules vary between local authorities.
The shift towards company ownership has a specific tax origin. Section 24 of the Finance (No. 2) Act 2015, phased in from April 2017 and fully in effect since April 2020, restricted the mortgage interest relief available to individual landlords to a 20% basic-rate tax credit, while limited companies retained the ability to deduct mortgage interest in full before corporation tax.
Sector-wide lending figures support the wider professionalisation trend. Paragon Banking Group reported that 43% of mortgaged buy-to-let purchases in Britain during 2025 were made through limited companies, up from 35% in 2024 and under 8% in 2018.
Landlords have traditionally had to choose between regions offering stronger rental yields and those offering long-term capital growth, according to Redwood Bank. The bank said rising rents, changing market dynamics and wider infrastructure investment have increasingly produced locations closer to home that can deliver both robust yields and capital appreciation at the same time.
Redwood Bank said this combination holds particular appeal for portfolio investors pursuing a sustainable long-term approach.
Worbey said professional landlords are now thinking more like business owners than they were a decade ago, weighing up income, long-term growth, operational efficiency and exit strategy together rather than basing decisions on yield alone. He described the choice of region as both a driver and an output of this shift in approach.
