Why am I being taxed on my student loan repayments?

[u123]

Using example figures, on my self assessment it says this

Income Tax charged £1000
plus Student Loan repayments £100

Income tax due £1100

The £100 is more than I've repaid this year in student loans repayments.
Could anyone explain this to me? The student loan repayment seems to be down so I can't even search on there to see what this is at the mo meant.

Ah, I think I've worked it out but confirmation if I'm on the right track would be appreciated.

I think because I've earned other money outside of my PAYE job, I am paying extra student loan repayments which is what that £100 is.

You've understood correctly.

Yup, the repayments are based on your total income.
Your PAYE job has taken the bit that relates to that income
your SA return picks up the rest

Thanks!