HELP Sample assessment 2, Task 1.7

Hi,

I was wondering if someone could help, apologies if this question has already been asked and answered.

Bob is a sole trader and employs Joan as his secretary. She is his only employee.
Joan earns a salary of £16,000 in 2016/17. She does not receive any benefits in kind.

Complete the following sentences by placing your answer, to the nearest whole pound, in the boxes provided. If your answer is zero, enter '0'

The total Class 1 National Insurance Contributions payable by Joan in 2016/17 are :
£16,000-£8,060=£7,940 £7,940 x 12% = £952.80 = £952 (this is also the answer provided so I know it's correct

The total employer Class 1 National Insurance contributions payable in 2016/17 are:
Why is the answer £0?

Your assistance is much appreciated
A.