Recovery of social security contributions: employers may recover from contractors; contractors may only deduct employee shares from wages. Section 17 permits an employer to recover from a contractor all contributions and administration charges payable in respect of an employee, either by deduction from contract payments or as a debt. A contractor may recover only the employee's contribution from the employee by wage deduction. Contractors are expressly prohibited from deducting or recovering the employer's contribution or administrative charges from an employee's wages.