NIM29027 | Special cases: Class 1 - mariners: host employer, mariner works in category A, B, C or D waters - existing legislation dealing with mariners
From HM Revenue & Customs · National Insurance Manual
Part 9, Case C of the Social Security (Contributions) Regulations 2001 (SSCR 2001) (SI 2001 No 1004)
For mariners and their employers SSCR 2001 gives effect to the policy objective of successive Governments to protect the benefit entitlement of mariners by extending their ability to pay NICs beyond the shores of the UK in certain circumstances.
For the purposes of this guidance it is assumed that the mariner is not on a vessel where the EC Regulations or a Double Contributions Convention/Reciprocal Agreement applies.
NIM29008 sets out the definition of a Mariner.