Platform has loosened some buy-to-let remortgage stress tests from 145 per cent to a minimum of 128 per cent of rental cover.
The intermediary arm of the Co-operative Bank will keep applying a notional interest rate of 5.5 per cent.
The move will help landlords who took out mortgages before new PRA affordability rules came into effect in January 2017.
The lender will let this group access pound-for-pound remortgages without any extra capital raising.
Other buy-to-let applications will continue to be stressed at 145 per cent at 5.5 per cent.
The Co-operative Bank and Platform head of mortgages and insurance Paul Norcott says: “We have been closely following developments in the buy-to-let market since the new PRA guidelines were published, and we know that buy-to-let remortgaging has been more difficult for some landlords since the market adopted those guidelines.”