Your Class 4 National Insurance contributions (NIC) for any tax year are based on your profits for that year.
For 2019 - 20 you pay:
You pay additional contributions on the difference between your personal allowance and the amount on which you pay Class 4 NIC. For 2019 - 20, this difference is £3,868.
For further information and for previous tax years, see the table below. You can also read more about this on the HMRC website.
| Financial years | Personal allowance (PA) | Lower limit | Difference | % Charged for income between lower and upper limit | Upper limit | % Charged for income above upper limit |
| 2019-20 | £12,500 | £8,632 | £3,868 | 9% | £50,000 | 2% |
| 2018-19 | £11,850 | £8,424 | £3,426 | 9% | £46,350 | 2% |
| 2017-18 | £11,500 | £8,164 | £3,336 | 9% | £45,000 | 2% |
| 2016-17 | £11,000 | £8,060 | £2,940 | 9% | £43,000 | 2% |
| 2015–16 | £10,600 | £8,060 | £2,540 | 9% | £42,385 | 2% |
| 2014–15 | £10,000 | £7,956 | £2,044 | 9% | £41,865 | 2% |
| 2013–14 | £9,440 | £7,755 | £1,685 | 9% | £41,450 | 2% |
| 2012–13 | £8,105 | £7,605 | £500 | 9% | £42,475 | 2% |
| 2011–12 | £7,475 | £7,225 | £250 | 9% | £42,475 | 2% |
| 2010–11 | £6,475 | £5,715 | £760 | 8% | £43,875 | 1% |
| 2009–10 | £6,475 | £5,715 | £760 | 8% | £43,875 | 1% |
| 2008–09 | £6,035 | £5,435 | £600 | 8% | £40,040 | 1% |
| 2007–08 | £5,225 | £5,225 | 0 | 8% | £34,840 | 1% |
| 2006–07 | £5,035 | £5,035 | 0 | 8% | £33,540 | 1% |
| 2005–06 | £4,895 | £4,895 | 0 | 8% | £32,760 | 1% |
| 2004–05 | £4,745 | £4,745 | 0 | 8% | £31,720 | 1% |