Approximately €2.2 billion wen unspent in 2021 across a number of areas, including health, housing and transport.
According to the Irish Examiner, despite exchequer spending reaching €87.54 billion, total capital and current spending was €1.38 billion below what was forecast for the year.
The overall spend figures also includes capital funding to the tune of €820 million which has been rolled over to 2022, increasing 2021's underspend to €2.2 billion.
Concern has been raised regarding the significant amount of money left over, with Independent TD Sean Canney, a member of the Budgetary Oversight Committee, warning that project targets will be missed as a result.
"I am concerned at the underspend in housing, transport and health infrastructure," Mr Canney said, calling for the funds to be used on projects which are ready to go.
He also suggested the unspent money could be reallocated to other departments which could deliver projects quickly to the benefit of communities.
"There is not shortage of projects and we need to keep providing the necessary infrastructure," he added.
Mr Canney, who represents Galway East, named Phase 2 of the Western Rail Corridor as a project which could benefit from the funds, as it could "commence construction within a matter of months as if does not require planning or any other statutory consents," he claimed.
Up to 10 per cent of unspent capital allocations may be rolled forward to the next year, subject to approval, with the portion of last year's unspent funds due to be dispersed across 19 areas. Housing, local government and heritage (€276 million), transport (€161 million) and health (€104 million) are among the areas due to benefit.
The remainder of the unspent funds, an estimated €795 million apportioned for current and €580 million for capital spending, has been surrendered to the Exchequer for 2021.