Confirmation of Paying via Tax Code

Hi all, I completed my first self-assessment due to a change in job role/salary that took me over the family threshold for receiving child benefit during the year, which meant that I need to repay £1300. I completed the self assessment and confirmed that HMRC should collect the outstanding amount via tax through my tax code for 2023/24. Within 24hrs of making this submission, I received an email to advise that my tax code has changed. My code changed from 1257L to K28 M1. However, I keep getting letters and emails from HMRC since then advising that I MUST pay by 31st January 2024 or risk a fine, unless I have an alternative method of paying set up (such as via tax code). However, I have nothing in writing to confirm that payment will be taken from my tax code. I can't call HMRC to ask since I can only call to make a payment, and the online chatbot just keeps directing me to make a payment. So I'm totally at a loss at how to get help on this. How do I know if I am 100% confirmed to make a payment via my tax code, and therefore not going to risk missing the 31st January deadline?

Hi Hmrc admin. Any chance of a comment on this one please? Seeing plenty more answered ahead of this. Thanks, Dave

Hi deadpandave,
You can call HMRC, or contact us via webchat, to discuss any aspect of your PAYE and Self Assessment records, including whether your balancing payment is now included in either your current year or 24/25 tax code. Contact us via Self Assessment: general enquiries and we can confirm how you can pay your balancing payment.
Thank you.