CSLM10014 - FAQs: employers questions and answers: new employee: P45 has a 'Y' in the SL box - t/p has repaid loan
Suggested answer
Continue to make Student Loan and or Postgradaute Loan deductions unless you have received a Stop Notice.
When a loan has been paid in full, Student Loans Company (SLC) will notify HMRC and a Stop Notice will be issued to you.
If deductions continue after a Stop Notice has been issued, a GNS prompt will be sent to your online account as a reminder to action the Stop Notice.
You can find more information about Stop Notices on gov.uk