Sparks Accounting
02392 008 665

For sole traders and partners.

Self-Assessment Calculator

Estimate your Self-Assessment bill, including Income Tax, National Insurance and Payments on Account.

Start your estimate

Calculate your Self-Assessment bill

Built for sole traders and partners. Enter your trading income, expenses and any other taxable income, then see your Income Tax, National Insurance and any Payments on Account for the year you select.

Other taxable income

Estimated tax bill

Trading profit
£39,600
Total taxable income
£39,600
Personal allowance used
£12,570
Taxable income
£27,030
Income Tax
£5,406
Class 2 National Insurance
£0
Class 4 National Insurance
£1,622
Estimated total
£7,028
Payments on Account
Because your bill is above £1,000, HMRC asks for advance payments towards next year's tax.
31 January payment
£10,542
31 July payment
£3,514

Estimate only. We will confirm your figures in a free consultation.

Based on England and Wales 2026/27 Income Tax bands and Class 4 National Insurance for the self-employed. Dividend and interest allowances are not modelled in detail.

Your Self-Assessment estimate is ready to send.

Fixed-fee Self-Assessment filing

Standard Tax Return

£198

For sole traders and landlords with one source of self-employment or property income.

Partnership Tax Return

£450

Full partnership return prepared and filed, including partner statements where required.

Partner in the Same Tax Year

£330

An additional partner return linked to a partnership filing in the same year.