Class 4 NICs: computation of liability: summary
The following sections look at the computation of the Class 4 NICs profits.
The self-employed pay Class 4 NICs on profits immediately derived from the carrying on of a trade, profession or vocation (SSCBA92/S15).
This guidance relates to periods after the introduction of Self-Assessment. For guidance on earlier periods contact CTIS (Technical).
Guidance on deferment can be found in the National Insurance Deferment Manual.