NatWest had made changes to its buy-to-let calculator and wider offering for landlords.
It has reduced the minimum rental coverage ratio from 125% to 100% for customers whose total personal income is £75000 p.a. or more (sole income.)
Basic Rate Tax relief will be applied for buy-to-let property finance costs when assessing affordability.
The lender says it has also improved its approach to how it treats residential monthly rent payments for non-home owners when assessing affordability.
NatWest said that brokers should ensure all buy-to-let applications are checked using the calculator on its website before submitting to confirm that they meet lending requirements.