My son (18) works occasional casual shifts at a sports centre, earning well below the tax threshold. After eventually conquering the timesheet process, he has now got his first payslip. Tax has been deducted, so he obviously didn't fill in a Starter Checklist when he joined. I've recommended that he emails HR, to sort it out going forward. But will they pay back the previous tax, or will he need to claim it via HMRC?