The Department of Education has apologised for a fault in its payroll system that has led to sums of money being incorrectly deducted from the wages of teachers and other staff working as substitutes in schools.
It said it is working "intensively" to resolve the problem.
It said that refunds of tax "deducted in error" will begin to be paid to post-primary substitute teachers from next Thursday, and to primary school teachers the week after.
The problem has arisen as a result of the modernisation of the PAYE system.
The system is treating many substitute teachers and other non-teaching staff as new employees, and is deducting emergency tax from their pay.
The Department said a permanent fix is currently being tested and is expected to be successful.
Frustrated teachers have complained that up to 55% of their income has been deducted as tax this month, because of the system's failure to recognise their tax credits.
One substitute teacher told RTÉ News; "This is going on for over a month with no end in sight."
She complained of what she felt was "a distinct lack of immediacy" in the Department regarding finding a solution.
It is not clear how many workers have been affected. The Department has more than 9,000 substitute teachers on its payroll. However it believes that substantially fewer have been hit by this problem.
In a statement the Department said it is acutely aware of the inconvenience that is being caused by the problem. It said it is responding to taxation queries by email.
It said the problem emerged as a new modernised PAYE system was being implemented from 1 January.
Payroll files that transferred to Revenue under the new system inadvertently included an end date for substitute staff. This led to the removal of tax credits by revenue.
Teachers and other staff affected can contact the department via the following email addresses:
primtch_payroll@education.gov.ie for primary teacher substitutes
PPPayroll@education.gov.ie for post primary teacher substitutes
ntspayroll@education.gov.ie for non-teaching staff substitutes.
Dedicated phone lines are available for primary substitutes on 09064 84043; post-primary substitutes on 09064 84161; and non-teaching staff on 09064 84136.
