People with fixed-term mortgages due to run out could face paying an extra €5,800 a year.
Mortgage broker Doddl.ie is urging mortgage holders to shop around, as some on fixed rates of 2.5% could see that rate rise to 5.95%.
For those on a typical €250,000 mortgage, their monthly repayments could go up by €500.
That would mean on a €250,000 mortgage, their repayments could be an extra €5,800 a year.
Doddl managing director, Martina Hennessy, says we're in a cycle of rising fixed interest rates.
She also suggested that now is the best time to shop around if your fixed-rate mortgage term is due to run out.
"So those that our rolling out of fixed rates, maybe they have locked in 12 months or 24 months ago, on a very average 2.5% fixed rate, and rates were as low as 1.9%, will see themselves rolling out of fixed rates on to variable rates, which will start at roughly the 4% mark.
"There's a very big difference between lenders in the market and it's important to make sure when you roll out a fixed rate, that you take control of your mortgage, don't take a wait and see approach, and you look to see if you can save by reviewing your rate and seeing if you can switch to another provider."