A bonus or RSU vesting is taxed as ordinary employment income in Ireland, stacked on top of your salary — usually at your highest marginal rate since it arrives on top of income you've already earned that year.
The bonus or RSU value is added to salary to compute total income for Income Tax, USC, and PRSI, all calculated on the combined figure. Because it's added on top, it's effectively taxed at whatever your marginal rate already is — commonly the 40% Income Tax band plus 3-8% USC plus 4.35% PRSI for anyone already above the standard rate band.
At vesting, no — RSUs are taxed exactly like a cash bonus: Income Tax, USC, and PRSI on the market value of the shares on the vesting date. The difference comes later: if you sell the shares for more than their value at vest, that gain is subject to Capital Gains Tax at 33%, after an annual €1,270 exemption.
Usually via PAYE, yes, but bonuses and RSU vests can sometimes be under-withheld if payroll doesn't correctly project your full-year income — worth checking this calculator against your payslip, particularly in the month a large bonus or vest lands.
Figures are estimates for informational purposes only, based on the assumptions you enter, and are not tax advice. Consult a tax advisor or Revenue.ie before making financial decisions.