Car benefit for employee and NIC

Hi sir,

There was a question in BPP kit in which they asked to advise the employee of Income tax & NIC implications if he’s provided a company car, and advise employer of corporation tax and NIC on the same thing.

My thought was with the car benefit, employee will have additional taxable benefit of x% on car listing price and no changes on NIC Class 1. The Kit answers the same.

But for employer side, they calculated employer Class 1A NIC on the car benefit, which then reduce employer’s corporation tax.
I’m a bit confused on this part, isn’t employer’s NIC also calculated based on employee’s earnings? If the taxable car benefit was not included in the calculation for employee’s NIC, why is it included here please?