In Ireland, R&D claims must be filed 12 months from the end of the accounting period in which the qualifying R&D expenditure was incurred. If the deadline is missed, no entitlement to any amount in that period arises.

To offset unused credits against the Corporation Tax liability of the preceding accounting period or to have the excess credits paid by Revenue in three instalments, complete the relevant section of the Form CT1. Claims for the three instalments cannot be paid before the 21st day of the 9th month following the end of the relevant period, or 12 and 24 months respectively following that date.