Market Harborough Building Society has announced a relaxation of its interest rate stress testing criteria across residential mortgages up to £5 million, extending the move to include expat scenarios.

The change, which affects a broad range of complex cases, will increase affordability for many borrowers, enabling clients to access higher loan amounts under the Society’s specialist lending proposition.

The updated stress rate means that borrowers, including high net worth individuals and those looking to remortgage, may now benefit from enhanced loan capacity.

New customers are also expected to gain from the shift, particularly those seeking more flexible underwriting for residential purchases or refinances.

As an illustration, a household with £100,000 in annual income seeking a residential repayment mortgage on a two-year discount rate could now borrow up to £55,000 more under the revised approach. The figures are based on the Society’s tier two residential product, up to £3 million, currently priced at 5.49%.

The change is part of a broader effort by Market Harborough to remain competitive in the specialist lending market, where clients’ financial profiles often do not fit mainstream criteria.

The lender already offers a suite of flexible solutions, including multi-generational lending, joint borrower sole proprietor (JBSP) arrangements, interest-only options, and a no loan-to-income cap across its product range.

Commenting on the update, Iain Smith (pictured), head of mortgage distribution at Market Harborough, said: “Easing our residential stress testing is another step in making our mortgage solutions even more accessible.

“We’re seeing a welcome market shift in how affordability is assessed, and these changes are designed to support more clients with complex needs on top of what we’re already offering, including multi-generational and JBSP solutions, interest-only deals, and no LTI cap across our products.

“It’s all part of our commitment to evolving with the market and listening to our brokers to provide flexible solutions that meet real-world client needs.”

The announcement follows Market Harborough’s recent decision to increase the maximum loan size across its standard residential range to £3 million.