US Expat UK Employed and “Self-Employed” Tax Return Query

Hello everyone,

I was wondering if the nice people would be able to offer help to someone who has a job and has now earned a little extra on the side.

I am US Expat and have been in the UK for about 8 years now. I am employed and I earn a salary from an employer/PAYE. In 2021, I had additional income on top of my full-time/PAYE employment income.

In the UK for the additional self-employed income part this requires a simple self-assessment form and as my turnover is under £85,000 I have not separated all my expenses. Only total income and expenses are required. Then I pay any additional income tax and NI on top of anything already deducted directly from my PAY/PAYE. Nice and simple.

My numbers converted to USD are a salary of about $70,000. Additional income of approximately $20,000. These are professional services, which entail a small amount of expenditure.

My usual US tax return for my employment income is simpler.
1040
1040s1
1040sb
F2555
fbar

I note on Form 2555 Part IV 2020 Foreign Earned Income where I usually list my total salary in box 19 that there is box 20a “In a business (including farming) or profession”.

Can I add my extra income (gross or net) here and be done? If I did, are there any additional forms required?

Or is there another simple way to do it correctly?

Having looked at Appendix C and 1040SE, I’d like to avoid those forms if possible. Or do I have to complete them? Are there any additional forms to fill out?

Thank you in advance to those who take the time to read and respond. Much appreciated.