There are claims that some landlords are deducting unnecessary cleaning fees from deposits.
According to the Irish Independent, landlords are issuing tenants with fake cleaning invoices so as not to pay back the full amount.
One tenant is reported to have lost €180 and an invoice was issued to another tenant for a cleaning company that was not officially registered.
Housing Charity Threshold has said the illegal retention of deposits continues to be an issue in the private rented sector with the Residential Tenancies Board reporting 1,234 disputed cases.
They told Independent.ie: "A deposit will often represent the full extent of an individual or family’s savings, and the failure to return the deposit creates a significant obstacle to obtaining alternative accommodation and can be the first step towards homelessness.
"Threshold has been calling for a legal definition of a deposit to mean one month's rent. We are aware of instances in which people are required to provide two months’ deposit, along with the first month’s rent.
"The common practice regarding deposits is the equivalent of one month’s rent.
"Threshold calls for the immediate introduction of a Deposit Protection Scheme, as set out in the Residential Tenancies (Amendment) Act 2015.
"This piece of legislation provided for a deposit protection scheme in Ireland, with the Residential Tenancies Board functioning as custodian of deposits and their dispute resolution service being used to settle disagreements between tenants and landlords.
"Despite legislation having been passed by the Oireachtas in December 2015 the Deposit Protection Scheme not yet been commenced by the Minister."