CSLM11212 - FAQs: borrowers questions and answers: does my employer need to know the amount repaid?
Suggested answer
No, your employer does not know any details of your loan balance or deductions with previous employers. This is confidential between yourself and the Student Loans Company.
Your employer makes deductions based on each pay period separately and will only have a record of each periods deductions that they make.
You can find more information on gov.uk.