Please see below a response by TurboTax David D to a similar question:
Since you were married on December 31, 2018 you have to file as Married
Filing Jointly (MFJ) or Married Filing Separate (MFS). As a US Citizen
or a Resident Alien, you have two choices in filing your taxes.
Option 1
Treat
your spouse as resident alien for tax purposes. If you do this, you
will need to include your spouse's worldwide income in your US tax
return and it will be subject to US taxes. To do this follow these
steps.
- 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.
- List the name,
address and Social Security number (or Individual Taxpayer
Identification number) of each spouse. This
form will be attached to your tax return. You will need to attach this to your return and mail your return to the IRS.
- 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.
Option 2
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.
https://www.irs.gov/Individuals/International-Taxpayers/Nonresident-Spouse-Treated-as-a-Resident
