If your spouse is a nonresident alien and you file a joint or separate return, your spouse must have either a Social Security Number (SSN) or an Individual Taxpayer Identification Number (ITIN). ... If your spouse is not eligible to get an SSN, he or she can file Form W-7 with the IRS to apply for an ITIN.
https://www.irs.gov/individuals/international-taxpayers/nonresident-alien-spouse#:~:text=If%20your%20spouse%20is%20a,Taxpayer%20Identification%20Number%20(ITIN).&text=If%20your%20spouse%20is%20not,to%20apply%20for%20an%20ITIN.
https://www.irs.gov/zh-hant/taxtopics/tc857
