With effect from 1 May, the sister banks’ SVR will rise from 4.59% to 4.95%.
They said that the number of borrowers affected amounted to less than a third of its customers, with average repayments increasing by less than £30 a month.
The banks said this was the first increase in their SVR for more than three years and attributed the move to the increased cost of mortgage funding.
Until 31 July, both Clydesdale and Yorkshire will waive their standard mortgage exit administration fee for customers impacted by the increase who wish to remortgage to another provider.
Steve Reid, retail director at the banks, said: “While our SVR will continue to remain competitively below a number of other UK mortgage providers, the market and costs associated with providing mortgages have changed significantly in the three years since the rate last moved.
“We don’t take such decisions lightly and fully appreciate the impact this will have on some customers, but you only have to look at the narrow gap between longer-term savings rates and mortgage borrowing rates to see how things have changed.
“For instance, our five-year savings account is just 0.7% below the new SVR. With significantly more savers than borrowers, it is important that we balance the needs of all of our customers.
“This change will help enable us to continue to support savers and maintain the competitiveness of our deposit rates. Our commitment to the mortgage market, including strong support for first-time buyers as one of only a handful of lenders that have consistently offered 95% LTV mortgages, remains as strong as ever.”