Why does self assessment calculation show an amount owing when I'm on PAYE

I have been an employee getting paid via PAYE for the past four years but this year (21-22) my self assessment calculation is showing nearly £100 owing. Previous SA submissions since I became an employee have been zero. Is this normal?

Hi,

Underpayments of tax under the PAYE system generally occur because your tax code was incorrect. Customer Forum advisers are unable to access individual tax records, so you may wish to call our Income Tax team for more information.   

Income Tax: general enquiries                                                                  

Tax codes      

Thank you.