One in five rental sector tenants expects never to see their deposit cheque again after handing it over, according to research.
Some 20% of tenants surveyed for law firm Slater and Gordon expect to wave goodbye to their deposits forever.
And nearly three-quarters (72%) of tenants also said they have had to struggle to get back the sums they felt they were owed.
Four in 10 tenants said they had received none of their deposit back when leaving a property, with the average UK tenant having put down a security deposit of £549.
But the survey of more than 1,000 tenants and 500 landlords also found many landlords said tenants had caused more damage than the security deposit could cover.
Some 79% of landlords said they wished they had asked for bigger deposits from their tenants after damage to their property was not covered - including damage to the carpets, walls, appliances and furniture.
The most common reasons landlords and letting agencies gave for refusing to hand back a deposit were stains on the carpet, chipped paint and damaged wallpaper, broken or damaged furniture and broken or damaged windows, the survey found.
And 18% of tenants surveyed also admitted they did not bother to read their rental contract properly before signing it.
Samantha Blackburn, a property lawyer from Slater and Gordon, said it is "crucial" that all tenants read their contract thoroughly before signing, to avoid any surprises or disputes in the future.
She continued: "It is also important that landlords are in contact with their tenants and are monitoring the use or damage to the property throughout the tenancy."
Ms Blackburn said: "Security deposit disputes between landlord and tenant are a common problem and something we are seeing our clients experience more and more.
"If tenants are respectful of the property and leave it in the same condition as when they moved in they can reasonably expect to get their full deposit back."
Ms Blackburn said tenants should take photos of the property when they move in, keep a detailed inventory, and tell their landlord and make a note when any damage is caused.
She said: "Landlords should do the same and make sure what they are charging their tenants is an accurate security deposit to reflect any damage that might occur during the tenancy."
A Department for Communities and Local Government (DCLG) spokesman said: "Nearly 10 million deposits have been protected since the launch of tenancy deposit schemes and measures in the Housing and Planning Bill further crack down on rogue landlords and strengthen councils' powers to tackle poor-quality privately rented homes in their area."
He said it is important to remember that "the vast majority of landlords and letting agents provide a good quality service".