Reductions include the 70 per cent loan to value (LTV) mortgage which has been reduced by 0.12 per cent to 2.37 per cent.
And the 75 per cent LTV product has also been reduced by 0.13 per cent to 2.42 per cent.
Principality Building Society head of products Naveed Mohamed said: “We’ve improved the pricing on our buy-to-let range to ensure that our products meet the needs of our clients.”
The mutual will consider buy-to-let applications for new build properties, which it said was a growing market.
It will accept up to three buy-to-let applications per customer, depending on whether they hold existing mortgaged rental properties, and also first-time landlords.