You
can file married filing jointly or married filing separately if your spouse is
a non-resident alien. If the latter and your spouse have no US source income,
he/she would not be required to file. The IRS discusses the joint return
election here Note: to use the joint return the
non-resident alien would be treated for tax purposes as a US resident alien.
That means they would be taxed on their worldwide income, although the foreign
earned income exclusion may apply.
SSN or
ITIN If your spouse
is a nonresident alien and you file a joint return, your spouse must have
either a Social Security Number (SSN) or an Individual Taxpayer Identification
Number (ITIN). To get an SSN for your spouse, apply at a social security office
or US consulate. You must complete Form SS-5. You must also provide original or
certified copies of documents to verify your spouse's age, identity, and
citizenship. If your spouse is not eligible to get an SSN, he/she can file Form
W-7 with the IRS to apply for an ITIN. Refer to Taxpayer Identification Numbers
(TIN) for more information.