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HMRC internal manual

National Insurance Manual

Overview and purpose: the structure of the NIM

The National Insurance Manual (NIM) is broken down into seven main sections. These sections follow the six classes of National Insurance contributions (NICs) plus a section dedicated to Special Cases. This structure is broadly in line with the structure of the law relating to NICs.

The six Classes of NICs

The NIM covers the six classes of NICs. These are:

  • Class 1 (See NIM01000CO)
  • Class 1A (See NIM13000CO)
  • Class 1B (See NIM18000)
  • Class 2 (See NIM20000CO)
  • Class 4 (See NIM24000CO)
  • Class 3 (See NIM25000CO)

Special cases

The Special Cases section of the NIM covers:

  • Aircrew (NIM27000)
  • Continental Shelf Workers (NIM28000)
  • Mariners (NIM29000)
  • Married Women (NIM30000)
  • Widows (NIM31000)
  • HM Forces (NIM32000)
  • People Going to and Coming from Abroad (NIM33000)
  • Volunteer Development Workers (NIM34000)
  • People over State Pension Age (NIM36000)