Sebastian Stoecker

We are using the Basic PAYE tool from HMRC to operate payroll. One employee is working overseas and has been identified to be liable for social security payments in that other country. I understand that the UK employers obligation to pay social security follows the obligation of the employee and so the UK employer should not withhold any National Insurance in the UK. The employee has been issued a NT taxcode from HMCR already. My question: What National Insurance category letter do we use for this employee to operate payroll?