I wonder does anybody know how tax works on back pay. My employer was accidentally underpaying me for 10 months and I received the backpay today. I asked whether I would be taxed more given that the amount was so much more than I would usually receive in a month and the employer said it made no difference. Having said that, it appears that I have paid an enormous amount of tax! perhaps that's more to do with the rates of tax we pay here in Ireland and less to do with my employer but any advice would be very much appreciated.