NIM37019 - Refunds: retrospective change of employment status from self-employed (Class 2) to employed earner (Class 1)

Regulation 51 of the Social Security (Contributions) Regulations 2001 (SSCR 2001) (SI 2001 No 1004)

If a contributor pays Class 2 NICs when Class 1 NICs are due and the employer accepts Class 1 status, any wrongly paid NICs should be reallocated towards the primary Class 1 due.