Financial research firm Defaqto said more than half of home insurers now charged an excess of £100 or more, compared with a third three years ago.
It also emerged that eight out of ten travel insurance providers will charge more than one excess per claim.
Mike Powell, general insurance spokesman for Defaqto, said consumers needed to know that one incident – such as a mugging on holiday which leads to the theft of a bag – could result in more than one excess being applied.
He said: “The person would be charged an excess for the loss of the baggage and if there were personal items, passport or money, that is three more sections, each with their own excess.
“If they had suffered an injury they’d also be looking at medical expenses on top of that”, he added.
Other insurers would charge just a single excess for the same incident, he said.
“People need to ensure they read the details and small print before purchasing their insurance.
“They may think they’re getting a cheap deal but often this is not the case.”