National Insurance Manual

NIM01530 - Class 1 Structural Overview: zero-rate of secondary NICs for Freeport and Investment Zone employees: evidence

Employers should keep evidence of their right to use the Freeport or Investment Zone NICs category letters (see NIM01540). This evidence can be, but is not limited to, set out in a written agreement made between the Freeport or Investment Zone employee and the employer.

The agreement should contain the following information:

• The Freeport or Investment Zone special tax site that the employer expects their employee to spend 60% of their working time.
• The start date of the employment
• If different to the start date, the date from which the Freeport or Investment Zone employer expects the employee to spend 60% of their working time at the Freeport or Investment Zone special tax site business premises.

The written agreement is not restricted to the employment contract and can be a written communication between the employer and Freeport or Investment Zone employee.

Other forms of evidence could include entry logs or key card access records, or other evidence which demonstrates an employee’s presence in the employer’s business premises at the Freeport or Investment Zone special tax site.

Employers may also find it helpful to keep a record of the workplace postcode for each qualifying employee, as from 6 April 2025, an eligible employer operating in a designated Freeport or Investment Zone special tax site, and who wishes to claim the employer national insurance contributions relief, will be required to provide the workplace postcode for any qualifying employees within their RTI Full Payment Submission.