Employees and workers are protected from any unlawful deductions from their wages.
There are three general situations in which an employer is lawfully permitted to make deductions from the wages of employees:
If they are required or authorised to make deductions by law (eg PAYE).
If this is permitted under the terms of the employee contract (the written part of this contract, together with an explanation, must have been provided to the employee).
If the employee has consented to the deductions in writing (in advance of any deduction - and also in advance of any act or omission on the part of the employee which has led to the deduction).
Additionally, an exception under law applies in the case of an overpayment of wages - this allows employers to make a deduction in order to correct the error. For further information read Overpayment of wages.