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HMRC internal manual

National Insurance Manual

Aggregation of Earnings: More than one employment with different employers, only one of whom is treated as the secondary contributor for both employments

Regulation 15(1)(b), Social Security (Contributions) Regulations 2001

Regulation 15(1)(b) of the Social Security (Contributions) Regulations 2001 provides that if someone is employed by two or more different employers, one of whom is by virtue of the provisions of Schedule 3 to the Social Security (Categorisation of Earners)Regulations 1978 treated as the secondary contributor in each of those employments and each one pays them, the earnings from each employment shall be aggregated and treated as a single payment of earnings and NICs calculated on the total unless it is not reasonably practicable to do so (see NIM10009 for a discussion of the ‘not reasonably practicable’ test). The secondary contributor is liable for the NICs.