Student Loans and Self Assessment

Hi all, I am recently doing my self assessment. I selected all of the relevant choices: being on "Plan B" of student loan repayment and on an "Income Contingent Student Loan". My employer deducted £873 from my employment pay (visible on my P60) yet my final self assessment bill still asks me to pay £543 of "student loan repayments". Why is it asking me to double pay? Is something wrong with my calculation? Many thanks.

Hi wetorwetor2,
If you have income other than your PAYE income this will increase the student loan repayments.
Please see guidance here:
Repaying your student loan
Thank you.