Some renters have been unable to claim their Rent Tax Credit as it has been used to pay off tax bills from 2020.
Liabilities would have been built up as a result of government schemes at the height of the pandemic.
It's emerged Revenue Commissioners has used the Rent Tax credit to offset against bills accrued as a result of employees being on the temporary wage subsidy scheme.
The scheme was introduced in 2020, while the country was in lockdown as a result of COVID-19.
Anyone on the scheme received a subsidy from the public purse, but it was not subject to tax at the time.
Revenue committed that any tax liability built up as a result of this could be paid off over 4 years through reduced tax credits.
However, the rent tax credit has been used to offset against those bills in some cases - the extent of which is unclear.
In a statement, a revenue spokesperson says when two income tax returns are filed at the same time, a tax credit in one document could be used to offset against liabilities in the other.