The short version: SA103 is the self employment supplementary form. If you’re a sole trader, you use this to report your business income and expenses alongside your main SA100.
Which version do you need?
SA103S (short) if your turnover is below a certain threshold. SA103F (full) if it’s above. The threshold changes, so check gov.uk for the current figure.
What goes on it?
Your total business income, allowable expenses broken down by category, and your calculated profit. This feeds into your overall tax calculation.
Filing online?
The online system has self employment sections built in. You don’t need to download separate forms. But you do need to know what figures to enter.
Self employed and need to file? We can sort your return from start to finish.
