Martin Lewis' MoneySavingExpert has advised all homeowners to check their mortgage - as they could save thousands following the latest base rate rise.
Last week the Bank of England raised base rate from 1.25% to 1.75% - a rise of 0.5 percentage points.
If interest rates are higher, you'll pay more to borrow on products like mortgages.
Economists think base rate could reach 3% next year, meaning big rises in mortgage rates.
Now the latest MoneySavingExpert email said homeowners should check their deals now to offset rising home loan rates.
The email said: " Everyone with a MORTGAGE should check their deal now - some can still save £1,000s."
How much your mortgage rate will go up by depends what sort of deal you have.
If you have a fixed rate deal, your mortgage payments will not change until the end of your term.
Around 80% of UK homeowners have fixed-rate mortgages.
But almost a third (32.7%) of these have terms of two years or less, meaning many will come up for renewal this year or next.
Almost two-thirds (59.7%) have homeloan terms of five years or more, according to Bank of England data.
MoneySavingExpert said: "Yet if your fix ends within the next year or two, you're likely to have to pay more on a new deal."
People with variable-rate mortgages face paying higher rates much faster.
MoneySavingExpert said: "On a variable rate? Costs are likely to rise within weeks. If it's a tracker, it'll jump by 0.5 percentage points, which adds a hefty £25 or so per £100,000 of debt to a monthly payment.
"If it's a standard variable rate (SVR) - or linked to one - it's not certain to rise by the same amount, but it's likely to."
But you may be able to lock into a competitive mortgage rate now, before home loan rates start to go up even further.
Many lenders will let you sign up for a new mortgage up to six months before your current deal ends - but beware of early exit fees on some mortgages.
MoneySavingExpert added: "If either a) you're on an SVR, b) you can leave your deal penalty-free, or c) your fix or tracker ends within the next six months, then see if you could save with a new deal."
Moneyfacts data shows the cheapest rate for someone looking for a two-year fixed-year £200,000 mortgage now is 3.19%.
This is currently being offered by Progressive Building Society.
Over 25 years that works out at £968 a month.
If base rate does go up from 1.75% to 3%, if the 1.25 percentage point increase is passed on it would mean the above mortgage repayments going up to £1,105 a month.
That's an extra £137 a month, or an additional £1,644 a year.
