CSLM11013 - FAQs: borrowers questions and answers: can employer charge for making deductions?
Suggested answer
No. The legislation does not provide for a charge to be made by the employer on
an employee for making the deductions.
If your employer disputes this please ask them to contact HMRC.
Note: The employer is allowed to make a charge for certain other deductions,
for example, some Court Orders. This does not extend to Student Loans and or
Postgraduate Loan.