Self Assessment for Side Hustles: What You Need to Know

If you earn money outside your PAYE job, you almost certainly need to complete a Self Assessment tax return — even if you already pay tax through your employer.

When you must register

You must register for Self Assessment if your self-employed income exceeds £1,000 in a tax year (the trading allowance). Register by 5 October following the tax year end.

What you'll pay

• Income tax on self-employed profits at your marginal rate
• Class 4 National Insurance: 6% on profits £12,570–£50,270, 2% above
• Class 2 NI: £3.45/week if profits exceed £12,570 (voluntary below)

Expenses you can deduct

Equipment, software, home office costs (proportional), travel, professional subscriptions, and marketing spend can all reduce your taxable profit.

Work out your combined tax bill with our employed & self-employed tax calculator.