Lenders rejected one in seven homeowners who tried to remortgage in the past two years.
One in four of those who could not remortgage saw their monthly payments rise as a result.
Affordability rules and credit record issues were the main reasons for being turned down, according to research from Nottingham Building Society.
Its study found that missing out on a deal with an existing or new lender meant higher monthly costs for 26%, with 8% seeing a substantial rise in payments.
One in four said they were turned down either because they did not fit new affordability rules or because their credit record had deteriorated.
And 11% say they were turned down for being too old.
Ian Gibbons, senior mortgage broking manager for Nottingham Mortgage Services (NMS), said: “With rates remaining low it is potentially a good time to remortgage to a new deal but unfortunately it is not always that simple.”
He said homeowners need to think carefully and research the market. “People’s circumstances change and seeking help from a broker to get an independent view on the best deal available to a customer is a very sensible approach.”