Changes include a revision of the way annual mortgage interest is calculated.
For a standard buy-to-let application, if the landlord is going for a fixed rate of less than five years, it will use annual mortgage interest of either 5.5 per cent or the product rate plus two per cent.
For longer term products, annual mortgage interest of either 4.5 per cent or the product rate plus one per cent will be considered.
For like-for-like remortgages, annual mortgage interest of either 4.5 per cent or the pay rate plus one per cent will apply for all fixed rate terms.
Annual rental income should be more than 145 per cent of the annual mortgage interest to pass affordability.
These changes follow the launch of 95 per cent loan to value (LTV) residential mortgages, which were announced earlier today.