Santander will assess buy-to-let remortgages with 125% rental cover at 5% for borrowers who took out a mortgage before the Prudential Regulation Authority rules came into force.
The move, which will take effect from next Wednesday 19 April, is designed to prevent landlords from becoming mortgage prisoners.
In order to qualify landlords must have applied before 1 January 2017 and be remortgaging without attempting to borrow more, although adding product fees is permitted.
Brad Fordham, managing director of Santander for Intermediaries, said: “Some existing buy-to-let customers may be adversely affected following the new borrowing guidelines which were introduced across the industry earlier this year.
“Borrowers who have previously demonstrated they can meet affordability requirements may now find themselves restricted when it comes to remortgaging away from their existing lender.
“Through the introduction of these transitional arrangements, we hope to better support our buy-to-let customers, helping them to secure the best product to meet their needs when they come to renegotiate their product.”