£3k tax bill despite only income via PAYE

Hi all, How do I get my head around a £3k tax bill when my income was via PAYE, interest from my current account (£50!) and private medical which was already declared as part of my employment? Could it be that a salary change around March/April was not reflected in my tax code and hence I underpaid? This is my only plausible reasoning but then all salary changes are accounted for by HMRC when I look at my tax account online.

Hi

We would need to access  your record to check why underpaid. You can contact HMRC at Contact HMRC

Thank you