Q. Can I process a payslip for an employee that doesn't have an NI number?
A. The (very) short answer is yes.
You must obtain a National Insurance number if one is available. If the employee doesn’t have one, they must register for one as soon as possible. You can pay them and file your Real Time Information (RTI) submissions without the NI number, since it isn’t an HMRC technical requirement.
If you file an RTI submission without an NI number, HMRC will attempt to look it up and issue the relevant NI number, if found, via an electronic RTI notice. As and when your employee registers for one, HMRC may end up notifying you of the number before the employee does!
If the employee leaves before their NI number is issued, there isn’t any more that you can do and you didn’t do anything wrong. However, it is important to chase the employee for their NI number if they have one as it is imperative that you have checked they have the correct right to work.
Your payroll software may support the passport number field, which HMRC would like you to complete, if possible. However, again, it is not a mandatory requirement for filing, but it should be included where the passport number has been collected as part of the right to work checks.