Dublin City Council paid private landlords almost €149 million under two social housing schemes last year.
In total the state forked out over €626 million for the Rental Accommodation Scheme and the Housing Assistance Payment according to new figures from the Department of Housing.
The bill was 8 per cent or €47 million more than in 2020, as more tenants needed help with their accommodation needs.
Other counties with high figures include Cork, Louth, Kildare, Meath and Wicklow.
It comes as research from the ESRI shows over half of renting households got support for their housing costs in 2020.
In total 293,673 households received support, up from 134,973 in 1994. This amounts to 16 per cent of households overall and 54 per cent of those renting.
ESRI researcher Rachel Slaymaker says the problem is worst in urban areas;
"The most significant affordability challenges do tend to be within in Dublin and also particularly challenges around accessing these properties in the private rental sector under the limits for instance for schemes such as HAP."