Paper return Royal Mail delivery delay

Hi, Due to me being an non-resident I have to file a paper return each year, which I also did on 4/10 for this year through registered mail. I've now checked the relevant tracking number and I'm able to see that my return reached UK on 7/10 but has not yet been delivered to HRMC. Royal Mail says "item retention" at a local post office -Wolverhampton DO- since 14/10 (Saturday), whatever that means. I suspect that the delivery will be delayed further . I know that the deadline for a paper return is 31/10, so it has expired. I was wondering: a) Whether I'm now going to receive a penalty, even though I sent the return almost 1 month prior to the deadline and the final delivery is completely out of my control. b) How I can formally inform HRMC of all this, so I face no problem if the return is not delivered at all. Thanks in advance.

Can someone please respond to my queries? Thanks in advance.

Hi nickkaz,
If the tax return is not logged as received by 31 October 2023 and you received a late filing penalty then you would need to appeal against the penalty to review.
Hopefully the tax return will be delivered before the deadline date.
You can check if the tax retrun is now received by contacting HMRC:
Self Assessment: general enquiries
Thank you.

Thanks for the reply but I feel that my initial post has not been addressed properly. It is now 16/11, so the 31/10 deadline is definitely over. And I advised in my initial post that I know for a fact that my return has not yet been delivered to HMRC, because in Royal Mail tracking system I can see an "item retention" status in Wolverhampton DO since 14/10, hence without a delivery confirmation to HMRC. At this point I'm beginning to think that my return is lost or forgotten and this is completely out of my control. How should I act now before a penalty is imposed and how can I inform HMRC?

Hi nickkaz,
If your tax return was submitted 4 October and still not received by HMRC and you sent it by registered delivery and you have the address and recorded delivery reference number then you can contact HMRC to trace.
Self Assessment: general enquiries
If you do not have that information then you would need to resubmit the tax retrun and appeal any penalties charged for late filing. 
Thank you.