Your first Self Assessment tax bill: what you'll pay and when
In your first year self-employed nobody takes tax from your pay, so the whole bill lands at once, and January usually asks for half of next year's bill in advance too. Here's what to expect, with real 2025/26 figures.
On this page
Checked against GOV.UK on 23 October 2026. General information for sole traders in England, Wales and Northern Ireland, not tax advice. Scottish Income Tax rates are different.
When your first bill arrives
If you started in June 2025, your first tax year is 2025/26 (to 5 April 2026). You register by 5 October 2026, file online and pay by 31 January 2027. That can be 18 months of work before you pay any tax, so set money aside from the start.
What the first bill is made of
- Income Tax on profit above the £12,570 Personal Allowance: 20% up to £50,270, 40% above.
- Class 4 National Insurance: 6% of profit between £12,570 and £50,270, and 2% above.
- The first payment on account for the next year, usually half of the above, unless the bill is under £1,000 or more than 80% was already paid through CIS or PAYE.
Student loan repayments are added too, if you have one. See student loans and Self Assessment.
Worked example
Dan, a self-employed joiner not in CIS, invoiced £36,000 in 2025/26 with £6,000 of allowable expenses, so his profit is £30,000.
- Income Tax: (£30,000 − £12,570) × 20% = £3,486.00
- Class 4 NI: (£30,000 − £12,570) × 6% = £1,045.80
- 2025/26 bill: £4,531.80; first payment on account: £2,265.90
- Due 31 January 2027: £6,797.70. Then £2,265.90 on 31 July 2027.
If Dan were a CIS subbie with 20% (£7,200) taken from £36,000 of labour, he'd have paid more than his bill already: a refund of about £2,668.20 and no payments on account. See CIS refunds.
To see your own figures, use the January tax bill calculator for the balancing payment and payments on account, or the self-employed tax calculator for a whole-year estimate.
How to budget for it
- Move a fixed percentage of every invoice into a separate pot when you're paid.
- Once you're up to date, a Budget Payment Plan lets you pay weekly or monthly towards your next bill. See how to pay your bill.
- File early so you know the figure months before January.
This guide is part of our Self Assessment guides for the self-employed.
Free: The UK Contractor's Cheat Sheet 2026/27
CIS rates, overtime maths, tax dates, mileage, VAT and late payment, on 2 pages. Keep it on your phone or print it for the van.
Frequently asked questions
Why is my first tax bill so high?
It includes all your first year's tax plus a first payment on account for the next year, usually half as much again.
Do I pay Class 2 National Insurance?
For 2025/26, if your profit is £6,845 or more, Class 2 is treated as paid, so you don't pay it.
Can I pay my first bill in instalments?
You can pay in instalments before the deadline, or ask for a payment plan if you can't pay in full.
Sources
- Understand your Self Assessment tax bill: payments on account – GOV.UK
- Income Tax rates: previous tax years – GOV.UK
- Self-employed National Insurance rates – GOV.UK
- Rates and allowances: National Insurance contributions – GOV.UK
This guide is general information, not legal, tax or financial advice. Rules and rates change, so check the linked GOV.UK pages for the current position.