I hope this email finds you well and thank you for your query on the social security deductions shown on your payslips.
It is a legal requirement to pay Employees National Insurance if you are employed. The amount of contributions you have to pay will depend on whether you are an employed earner or self employed; and the amount you earn. As you are a contractor your national insurance is calculated at 11% on your basic pay, less a weekly/monthly allowance.
Employers Social Security is the National Insurance (NI) contribution that must be paid by all employers in addition to the payment NI made by their employees. In the current tax year Employers NI is calculated 12.8% less a weekly/monthly allowance.
As your employer we are required to make Employers NI contributions each time we pay your salary. These payments are a cost associated with your contract and are therefore deducted from the contract income when we calculate your profit bonus. You will see these cost clearly identified on the invoice reconciliation which can be found on the same page as your payslip in the payslip history section of your online giant portal.
I hope that has clarified the query for you but please let me know if I can advise any further.
Regards