Ordinary cash pay in Ireland, whether salary or a cash bonus, is taxed through PAYE, USC, and PRSI as soon as it's paid, and the employer owes Employer PRSI on top. The Small Benefit Exemption carves out an exception: up to €1,500 a year in non-cash benefits, such as One4All or similar gift cards, can be given to each employee completely free of all three employee-side deductions, and free of Employer PRSI too.
The catch is that it's genuinely all-or-nothing. A single voucher worth more than €1,500 loses the exemption entirely, its full value becomes taxable, not just the amount over the cap. The same applies across multiple smaller vouchers: Revenue allows up to 5 separate benefits a year, but if their combined value tips over €1,500, the exemption is lost on the excess benefit(s), and if more than 5 are given in the year, only the first 5 chronologically can ever qualify.
It also can't replace pay you would otherwise have received: a benefit provided under a salary sacrifice arrangement, where you give up part of your contractual salary or bonus in exchange for the voucher, does not qualify. It has to be a genuine extra the employer chooses to give.