Cascat

I returned from living in the US earlier this year, and had no tax liability to the UK for the tax year 2023-2024. I am now a UK resident, and will owe UK taxes for the 2024-2025 tax year. I have retired, and my income consists entirely of interest and dividends (no pension yet), almost all of which is from US based investments. This income will exceed the personal allowance and the savings and dividends allowance. As no UK tax is withheld at source, do I have to make any tax payments before I prepare my 2024-2025 tax return in 2025 or 2026? Is there any income or predicted amount of tax due where I would have to pay taxes early or inform HMRC of my income? If so, how and when do I need to do this? Or can I just leave doing anything until the end of the 2024-2025 tax year? Thank you.

I am a currently a non-resident UK citizen, resident in the US. I will be returning to the UK next year and will be a UK tax resident for the 2024-2025 tax year. Before I leave the US, I am trying to dispose of any investments I have that are not HMRC reporting funds, so the tax when I do sell will not to be subject to OIG. Since 2016 I have owned a US based ETF that was originally an HMRC non-reporting fund. In 2022, the ETF became a reporting fund. I have read in IFM13360 that IF I were a UK tax resident/payer during the transition from non-reporting fund to reporting fund, that I could elect to deem to have disposed of the fund and then rebought on the date it transitioned to a reporting fund, pay the tax due then, and then treat the gains going forward as HMRC reporting (and therefore capital gains not income). However I was not a UK tax resident on the date or year of the transition so this is not a declaration I could make or tax I would have had to have paid in that year. What would be the rule for this ETF, if I were to sell while UK resident and subject to UK tax, given that 1) I would sell whilst it was an HMRC reporting fund 2) the ETF would have been a reporting fund for the whole time I was a UK tax resident 3) The fund changed from non-reporting to reporting whilst I owned it, but before I became a UK tax resident, i.e. I bought and owned the ETF while it was a non-reporting fund, and it made significant gains while a non-reporting fund, but I was a non-UK resident for the entire time it was a non-reporting fund. Would all gains from the purchase in 2016 be subject to OIG tax, or as it was a reporting fund for the entire time I was a UK tax resident would it be considered normal capital gains?