If you legally live and work in the U.S. and you have a foreign spouse who lives abroad, it is possible for you to file a joint income tax return and save large amounts of money every year. For example, if you made $16,000 in 2008, and you filed as a single person with no dependents, you would have paid $2,000 in income tax. But if you had filed a joint income tax return with your foreign spouse, you would have only paid $1,600, saving $400. All you have to do is get a Taxpayer Identification Number ("ITIN") for your foreign spouse who is living abroad and attach the necessary documents to your income tax return. In order to file this joint income tax return, your spouse must either have a Social Security Number (“SSN") or an Individual Taxpayer Identification Number (“ITIN"). If your spouse does not fulfill the requirement to get a SSN, he or she can file Form W-7 with the Internal Revenue Service (IRS) to apply for an ITIN. When you decide that you want to file a joint income tax return, attach a statement signed by both you and your spouse to the return for the first tax year for which your decision applies. In this statement, you must include a declaration that your foreign spouse lived abroad and you were legally living and working in the U.S. on the last day of your tax year. You must write that both of you choose to be treated as U.S. residents for that entire tax year. You must also include the name, address, and SSN or ITIN of both you and your spouse. This law applies even if your spouse died in the tax year for which you are filing your tax return! You can even demand a prior tax return and re-file it jointly with your foreign spouse and get a refund of past taxes paid. If you and your spouse choose to do this, you and your spouse will also have to amend any tax returns that you filed after the year for which you made the choice. You usually have to file the amended joint return within 3 year from when you filed the original tax return you want to amend or within 2 years from when you paid your income tax for that year, whichever is later. After you make the decision to file jointly, your spouse will be treated as a U.S. resident, for tax purposes, for all future years. However, your spouse will no longer be treated as a U.S. resident if either you or your spouse decides that you do not want to file a joint income tax return any longer, if you or your spouse dies, if you and your spouse divorce or separate, or if you do not provide all of the necessary documents. If your spouse is no longer considered a U.S. resident for any of these reasons, neither you nor your spouse will be able to file a joint income tax return again for future years.