uniqueId

This field holds a unique identifier that you use to identify the employee, such as a works or payroll number. The unique identifier is a mandatory field for each employee in the /contributions request. The value provided will be returned in the /accounts/…/opt-outs response if the employee opts out of the scheme; it can be used along with niNumber to match against employees in the payroll.

These unique employee identifier values should not be reused for different employees within the same account.

If a unique identifier is changed from one contribution request to the next, we will use the other details to find the matching employee and update the value we hold.