New 90% LTV five-year fixed rates start at 3.60% with a £999 fee or 3.79% fee-free.
Santander is also launching new Help to Buy products with an extended nine month completion deadline.
New 60% LTV Help to Buy products include a 2.5-year fixed rate at 1.39% and a 5.5-year fixed rate at 1.83%, both with a £999 fee. At 75% LTV, a 2.5-year fixed rate starts at 1.87% with a £499 fee.
Selected existing Help to Buy rates will also see reductions of up to 0.25%. The largest reduction is to a 75% LTV five-year fixed rate which is now available at 1.84% with a £999 fee.
Other residential purchase and remortgage products between 75% and 85% LTV have been cut by 5bps.
Amongst the changes, charge end dates will roll on by one month to 2nd May and completion deadlines will roll on by one month to 5th June.
Santander confirmed that self-employed applications will continue to be temporarily restricted to 60% LTV.
