HMRC miscalculation on self-assessment income tax owed

I am an employee who earns over £100,000 so must complete a self-assessment income tax return. My employer has paid all my tax through PAYE and I have no other income. For the tax year 2022-23, though, HMRC says I owe an extra £2,265.70 in income tax. It appears that this is a miscalculation related to my £12,500 personal allowance. As my personal allowance is fully withdrawn, I should be paying 20% on that £12,500. Instead, it has been added to my 40% tax bracket. When you adjust for that error, my employer's tax payment on my income is correct. How do I get this fixed? I am being asked to pay the extra £2,265 or face a penalty.

Hi

As your income is over £100,000 you are not due full personal allowances.  See guidance at Income Tax rates and Personal Allowances

Thank you