HS304 supporting papers for US Residents and treatment of pension

1. I note that a certificate of overseas residence is not required for residents of the USA for HS304. Please advise what specific documentation if any is needed for US residents. In my case, I have been US resident since January 1, 2023 and will file a US resident 1040 tax return for the first time by April 15, 2025. 2. Am I correct is assuming that if I have UK sourced pension income and tax deducted at source for which there is full relief under the tax treaty, I do not include this in boxes 11 and 12 of TR3 of SA100 but I include this information in the table below question 3a of HS304?

Sorry, please note a typo above- I have been US resident since January 1, 2024, not 2023. Thanks

Hi,
You will still need to declare the pension on the return for the period that you are UK resident. The HS304 will show that you are now US resident from January 2024 in order to claim relief for the period January to April.
Thank you.