Why don't Class 1A National Insurances show up on the pay slip?

Class 1A National Insurances are due on most benefits, including payrolled ones, but they are calculated and paid separately from Class 1 National Insurances shown on the pay slip.

These employer-only contributions are reported and paid through the P11D(b) submission at the end of the tax year. They don’t affect the employee’s take-home pay and are typically not displayed on pay slips.

Class 1A National Insurances are calculated based on the annual value of the benefits provided and paid as a lump sum by the employer.