Get your taxes done using TurboTax

@dmclean222  Welcome to the states!! I will address your questions.

1. You can file as a US non-resident or you can file Married Filing Jointly (MFJ) with you spouse, provided if he/she is a US citizen or Resident Alien.  If you file jointly, you will need to report all of your worldwide income but if you file separately from your spouse as a non-resident alien, you would only need to report your US based income. At the end of these questions, I will address this filing more in detail.
2. If you file MFJ, you would report your UK side hustle as self-employed that is subject to Schedule C income.  Also you would report your employed income. Here is how to report both as these are treated differently.
3. For the side hustle.

• Go to federal>income and expenses>
• Self-Employment>Self-employment income and expenses 
• Complete the profile that asks about your business
• Then there will be a screen where you will enter your self-employment income. Here you will enter this as  other common income in the program. After entering income, you will start entering expenses into your program. 

       4. For the employment:

• Go to federal>wages and income>less common income> Miscellaneous Income, 1099-A, 1099-C>start
• Other reportable income>for description type in UK wages and then the amount.

       5. If you were taxed on this income in the UK, you may be able to claim a foreign tax credit since there is a taxation                   treaty between the two countries. To claim:

• Click on federal> Deductions and Credits at the top of the screen
• Select I will choose what I work on
• Scroll down to Estimates and Other Taxes Paid 
• Select Foreign Taxes and then select start

       6. Since you are in the US, this will still be reported on a calendar basis even though the UK tax season may be 

           different,

       7.  As I mentioned, if you and your spouse decide to file separately, you would need to file as a non-resident alien to 

            report only your US based income for the period of time you lived in the US in 2021. Turbo Tax does not support 

           non resident returns but our affiliate sprintax does.

Now the next issue is for you and your spouse to decide whether to file Married Filing Jointly or Married Filing Separately.

To do this follow these steps.

Choice 1- Married Filing jointly

   1. Attach a statement to your tax return, signed by both spouses, that states that one spouse is a nonresident alien and the other is a U.S. citizen or resident alien, and you are choosing to both be treated as US residents for the tax year.

   2. List the name, address and Social Security number (or Individual Taxpayer Identification number) of each spouse.  You will need to complete a Form W-7, Application for IRS Individual Taxpayer Identification Number (ITIN) (http://www.irs.gov/pub/irs-pdf/fw7.pdf).  This form will be attached to your tax return.  Turbo Tax does not support the Form W-7.  You can complete it outside of Turbo Tax.  You will have to print, sign and mail your return in if you are using Form W-7.

   3. For the first year you make the choice, you have to file a joint return. In later years you can file joint or separate returns. Married Filing Jointly will give you a higher standard deduction and has other benefits that are not available using a married filing separately status, but you do have to include your spouse’s worldwide income in joint income.

Choice 2 Married Filing Separately

• Treat your spouse as a nonresident alien for tax purposes. You will not have to include your spouse's non-US income on your U.S. tax return. You will have to use the filing status of Married Filing Separately. Remember though, your US based income will need to be reported on this return. 

If you have no US based income, you could be claimed as  a dependent on your spouse's return.  You will need either a social security number or an ITIN for your spouse to claim the exemption.

I hope this helps.