Notices of decision: Wording of National Insurance contributions liability decisions: Calculating Class 1 National Insurance contributions to include in decisions
When making National Insurance contributions (NIC) liability decisions you must have sufficient information to determine the liability for the period covered by the decision, in respect of the earnings for the earner named in the decision. The amount of the liability is the total of secondary and primary NIC due for the period covered by the decision. So, where the decision covers more than one tax year, you will have to calculate the liability for each tax year and aggregate the totals of secondary and primary NIC due for each tax year.
Where Class 1 NIC have not been paid or are underpaid, include a NIC paid decision with the NIC liability decision.