If you are a US taxpayer (citizen or resident alien) married to a non-resident alien you have two choices.
You can file as married filing separately. You do not list your spouse as a dependent. Include your spouse's ITIN. Married filing separately has the highest tax rates and many deductions and credits are reduced or disallowed.
Or, you can elect to treat your spouse as a US resident for tax purposes. This means you can file as married filing jointly, which has lower rates and better deductions. But it means you must report and pay US tax on your spouse's worldwide income (subject to a deduction for foreign taxes that they paid). Use their ITIN, unless they received a notification from the IRS that it expired. If the ITIN expired, you will have to apply for a renewal. Use the old ITIN but don't e-file. Print the tax return, and also download and print a form W-7 to apply for the ITIN (international tax ID number) for your spouse. Mail the tax return and the W-7 to the address in the W-7 instructions, not the normal tax return mailing address.
You can't file as single.
More info here,
https://www.irs.gov/individuals/international-taxpayers/u-s-citizens-and-resident-aliens-abroad-nonr...
https://www.irs.gov/publications/p519/index.html
https://www.irs.gov/uac/about-form-w7
