The review, which take effect from 26 April, requires lenders to make affordability a key consideration when offering funds.
Paul Field, West Brom director of operations, said: “We have been preparing for MMR for nearly two years now, while also running a major project to upgrade our application processing systems and boost residential lending volumes.
“Early adoption of the new requirements under MMR therefore made perfect sense as we were already making substantial improvements to our sales and processing capabilities.”
The building society reviews applicants’ income and expenditure against household composition, loan amount and the characteristics of their chosen mortgage product.
Estimated expenditure from households is also compared to corresponding data from the Office for National Statistics.
Field added: “We have been operating in an environment that reflects the fundamental principles of MMR for at least 12 months, with final policy changes being delivered over recent weeks that ensure full compliance for both new mortgage sales and contract variations for existing customers.”
Mortgages are available directly through 37 West Brom branches and over the telephone.