I understand that the trading allowance means if extra income payments total under £1000 then there is no need to do a Self-Assessment. Each year since 2004 I have had a variety of payments (organist fees, masterclasses etc) that invariably total more than £1000. I do a self-assessment and always declare this additional income. a) Should I be deducting £1000 from this total, since the HMRC calculation is not doing this for me? b) If I have overpaid tax on £1000 a year for the last 19 years, is there a way of claiming back the tax, and for how many years?