Class 3 NICs: time limits for paying Class 3 NICs: due dates
Regulation 48(3) of the Social Security (Contributions) Regulations 2001
Due date for payment
Class 3 NICs are due to be paid within 42 days of the end of the tax year for which they are being paid. However, they can be paid at a later date as long as they are paid within certain time limits, see NIM25028.
Due date for benefit purposes
If Class 3 NICs are paid within the time limits for benefit purposes but after the due date, they will only count for benefit from the date they are actually paid. For example, if someone pays Class 3 NICs within the time limits but after they reach State Pension age, their State Pension will only be increased from the date of payment and not from their State Pension age.