The Residential Tenancies Board has seen a 160% increase in the number of cases being taken by tenants in relation to rent, since the introduction of the 4% cap in rent pressure zones last year.
According to the RTB's annual report, renting is now the dominant housing tenure in many urban areas.
Since the introduction of Rent Pressure Zones in December 2016, the number of calls to the Residential Tenancies Board has increased from 600 to 1,000 a day.
According to the State body's annual report, more than half of all tenancies across the country are now covered by Rent Pressure Zones, and a 4% rent cap applies.
It has resulted in an increase in dispute applications by tenants about rent reviews with around 350 cases coming before the board, 75% of which were found in favour of tenants.
The RTB is encouraging existing or new tenants who are faced with increases above the rent cap to contact them.
Residential Tenancies Board is encouraging existing or new tenants who are faced with increases above the rent cap to contact them pic.twitter.com/qszBUadA2w— RTÉ News (@rtenews) August 30, 2017
It says that even if a tenant has agreed to a rent and signed a tenancy agreement, they are still protected under the law.
Speaking on RTÉ's Morning Ireland, RTB Director Rosalind Carroll said in terms of 2017, "the surge is absolutely as result of rent pressure zones".
She said the dispute cases they are dealing with are "a reflection of the supply restraint".
Ms Carroll said the three main dispute cases the RTB handles are rent arrears, notices of termination, and deposits.
She said "all are a reflection of what's going on in the market".