Should my husband file resident alien or nonresident ? He will file taxes with ITIN number. He doesn't have SSN but resides in the USA since 2000.

[CynthiaR · Accepted solution]

He would qualify as a resident alien.  Here is more information on this subject:

If the individual has resided in the U.S. for more than 31 days in the current year and has resided in the U.S. for more than 183 days over a three-year period, including the current year, he or she then would pass the substantial presence test and be classified as a resident alien at that time.

Resident aliens are taxed on all income as if they were a citizen of the United States, but a nonresident alien is subject to taxation only under specific circumstances. For a nonresident alien, only income that is generated from sources within the United States, excluding certain investments, is subject to taxation.