Asked to pay tax (1 balancing payment) but am PAYE?

Hi, I'm a full time employee taxed through PAYE, have completed my tax return and have declared nothing taxable except my full employment. However there is a an approx 2k difference between income tax due and income tax paid which I am requested to pay, but how is that possible when I am taxed via PAYE and there have been no changes in my tax code etc?

Hi,
It could be if your income was over £100,000 for the tax year and you received the full personal allowance £12570 in your tax code.
Once your income goes over the £100,000 threshold your personal allowance is reduced by £1 for every £2 above the threshold.
If you contact HMRC we can review the calculation for you:
Self Assessment: general enquiries
Thankyou.