NIM01540 - Class 1 Structural Overview: zero-rate of secondary NICs for Freeport and Investment Zone special tax site employees: category letters

It is the employer’s responsibility to ensure the correct category letter has been applied to the assessment of NICs based on the circumstances of the employee.

Before applying the zero-rate of NICs for Freeport or Investment Zone special tax site employees, the employer should confirm that the Freeport or Investment Zone qualifying conditions for both the employer and the employee are satisfied - see NIM01510 and NIM01515.

The following National Insurance category letters should be used to apply the zero rate of secondary NICs:

Freeport category letter	Investment Zone category letter	Description
F	N	standard rate contributions
I	E	married women and widows entitled to pay reduced contributions
S	K	employees over state pension age
L	D	employees who can defer National Insurance contributions

There is no category letter for mariners with the foreign going rebate. Employers of mariners with the foreign going rebate will need to claim the Freeport or Investment Zone relief after the end of the tax year (see NIM01560).