Explain the main differences between the primary and secondary Class 1 National Insurance Contributions (NICs).

b) Mark is a company director. His monthly salary is £8,000. During the year 2020-21, he is provided with a petrol-engine car with an emission rating of 112g/km. The car had a list price when new of £28,000 and was registered on 5 February 2019. All fuel and other related costs are paid by the company. The company also provides each of its senior management staff with private insurance cover of £1,800 yearly. Calculate the NICs payable with regard to Mark for 2020-21.