Hi turty3
There are two types of trivial pension:
(i) the pension benefit is less than €330 p.a. (and not created as a result of commutation). In this scenario, the tax rate is 10%.
(ii) the circumstances described by SBarrett above. In this scenario, the lump sum is subject to tax and USC like any other income in the tax year. So, the tax and USC payable, if any, depends on your mother's income position generally.