Foreign Employment Income Tax

Hi, During the 2024-25 tax year, I will stop working as an employee in England, work for three months as an employee in the US (internship for PhD students), and then return to the UK. If this is relevant, I'm a UK tax resident and not a US citizen. I wanted to ask for advice on the following questions. 1. Do I have to do a UK self-assessment and report the income I gained in the US? I assume that the answer is yes. 2. How should I avoid/minimize double taxation on my US income? As far as I know, there is a tax treaty between the US and the UK, although I'm unaware of its benefits and the steps I must follow to adhere to it. Also, my income will be taxed at source in the US. 3. If I'll be taxed in the UK on my US income, how could I estimate it? In short, I would like to know how to minimize double taxation and not miss any necessary proceedings. Best regards, 

Name removed admin .

Hi Manuel Carrasco,
Please have a look at the guidance at RDR3: Statutory Residence Test (SRT) and take the residence tests.  
If you are considered tax resident in the UK for the whole tax year, you should then look at split year treatment.  
If split year treatment does not apply, then you should declare your USA earnings, as they will be taxable in the UK.  
You would need to determine if you will be taxable in the USA on your income there (we cannot advise you about this).  
If you are taxable in the USA on your income there and in the UK, you would claim up to 100% foreign tax credit relief, so that you do not pay the same tax twice.
Thank you.

Thanks for your answer. I will be a tax resident in the UK and taxed in the US on my income. If I follow you, I must do my Self-assessment in the UK, report all my incomes, including the US one, and then apply for a 100% foreign tax credit relief. Does this 100% mean that I won't pay any taxes in the UK for my US income (already taxed in the US)? I'd like to understand better what this percentage refers to and to what it is applied. Thanks again for your help.

Hi
You can claim up to 100% of the foreign tax paid, if the UK liability is more than the foreign tax paid or up to an equivalent amount of foreign tax paid, to match the UK liability if less.