The West Brom is improving rates by up to 0.40% for borrowers looking to fix their mortgage over three years.
The building society has lowered its flagship three year product from 2.25% to 2.15% fixed until 31 August 2016.
This market leading rate is available directly from the West Brom at a maximum loan to value (LTV) ratio of 65%.
Applicants can borrow between £25,001 and £250,000. There is a £99 booking fee, plus a £1,895 completion fee, and the overall cost for comparison is 3.6% APR.
For borrowers with a smaller deposit, the Society's three year mortgages at 80% LTV are also now more affordable.
The rate for new purchasers has been reduced from 3.25% to 2.85% fixed until 31 August 2016. For customers who are remortgaging, the rate has fallen from 3.35% to 2.95%, also fixed for three years.
These mortgages are available directly through the West Brom's branch network or over the phone, as well as via selected intermediary partners.
Each has a £99 booking fee and a £995 completion fee. A free first standard valuation, worth up to a maximum of £525, is included, while remortgage customers also receive free standard legals. The overall cost for comparison on both products is 3.8% APR.
The West Brom said these latest improvements to its mortgage range reflected its commitment to providing a competitive offering and widening choice for customers keen to fix their rate of interest.