Can an Illegal Alien That's Married to a U.S. Citizen File Taxes?

If you are a "resident alien," according to the IRS rules, then you owe taxes on all U.S.- and foreign-source income. The IRS considers you a resident alien if you have a green card (as a lawful Permanent Resident) or if you pass the "substantial presence" test. The test requires that you add up all the days you were present in the United States in the last three years, according to a formula. More specifically, you must be present for at least 31 days in the current year, and for at least 183 days during the last three years -- counting all current year days, 1/3 of the days in the prior year, and 1/6 of the days in the previous year.

If you pass the substantial-presence test, you're a resident according to the IRS, even if you're undocumented. You must report money you earn in the United States and elsewhere, no matter where in the world you earned it, and pay taxes on it. If you also paid foreign taxes on that foreign-source income, then you may be able to take a deduction or tax credit for a part or all of the foreign tax amount. Your marital status makes no difference; you owe the IRS whether you're married or single, and no matter what the immigration or citizenship status of your spouse may be.

If the IRS considers you a "nonresident alien," then you still may be required to file a return. In the specific language of the Internal Revenue Code, you must file if you are "engaged in a trade or business in the United States," even if you have no U.S.-source income or your income is exempt from tax. If you are a nonresident alien, and you only earned U.S.-source income, you don't have to file if the income was less than the personal exemption amount ($3,900 in 2013). Note that "nonresident alien" does not mean "undocumented." The IRS makes no determination on your immigration status and does not apply that status to tax-filing requirements.

You must also file a tax return if you are claiming a refund from withholding, or from an overpayment of U.S. taxes. You must file if you intend to claim deductions or credits against your tax liability. If you are a non-resident, according to the IRS guidelines, you use Form 1040NR or 1040NR-EZ, rather than the standard Form 1040s. If you do not receive income subject to U.S. withholding, then your filing deadline is June 15. Residents and non-residents can file for extensions, just as ordinary U.S. taxpayers can. Before you leave the U.S., you must file Form 1040-C or Form 2063 for a Certificate of Compliance (also known as a "sailing permit") from the IRS, showing that you've reported income and paid taxes according to the law.