I just completed my SA for 2023/24 and after 24 hrs of the date updation, An interest was applied citing reason of overdue tax payment from July to Sep 2024. The fact that in SA i had to fill in the foreign income information which only becomes available by September in my home country, there was no way I could have completed the SA by July 2024. For e.g. by Sep 2024 I would know from my home country if the taxes that I paid there should be used as relief for UK SA or not. So if the taxes are returned then i cannot use that as tax relief in UK. So my question is why does HMRC levy interest when the final date of filling the SA for 2023/24 is 31 Jan 2025? How can I appeal (if i can appeal) for this interest that has been applied to me?