CSLM10016 - FAQs: employers questions and answers: new employee: P45 with no 'Y' in the SL box - t/p is a borrower
Suggested answer
If the employee states they are a borrower, you should ask them to confirm their plan or loan type, or both, and start taking deductions from the next available pay date.
If they do not know what loan and or plan type they have, the employee can log into their online student loan account or access gov.uk website for more information.
You can use Plan 5 as a default plan type in your payroll software until you get a student loan start notice (SL1).
You can find more information on the gov.uk website.