My husband never has been in the U.S. Can I apply for an ITIN for him to enter to my tax return? Or I should file as single?

According to the IRS, if you are a U.S. citizen or resident alien married to a nonresident alien (NRA), you are considered “Married Filing Separately” unless you qualify for a different filing status. (see US Tax Guide for Aliens for additional information)

So you have three main options for filing:

Since your spouse has not been in the US, if you file as married filing jointly and your NRA spouse lives outside the US and meets the Bona Fide Residence Test, your NRA spouse might be able to claim an IRS - Foreign Earned Income Exclusion that would exclude a portion of your NRA spouse's foreign source income (up to $100,800 for 2015).  TurboTax will guide you on taking the foreign earned income exclusion when you enter your NRA spouse's foreign source income under Federal Taxes> Wages and Income>I'll choose what I work on (or jump to full list)> Less Common Income (show more)> Foreign Earned Income and Exclusion

• Option 1 - Married Filing Separately (includes head of household (HoH), if you have a "qualified relative"- see US citizens and Resident Aliens Abroad - Head of Household) and you take no exemption for your NRA spouse
• leave NRA spouse's SSN blank and print a paper copy of your tax return
• hand-write "NRA" in all of the places on your tax return that require your NRA spouse's SSN (IRS - Married Filing Separately)
• mail in your return (you will not be able to efile your tax return so choose "file by mail" in TurboTax)
• mail to IRS address printed with your return
• Option 2 - Married Filing Separately (or HoH) and you claim an exemption for your NRA spouse (You can claim an exemption for your spouse only if your spouse had no US source income, isn't filing a US tax return, and isn't the dependent of another person other than yourself)
• leave NRA spouse's SSN blank and print a paper copy of your tax return
• apply for NRA spouse’s Individual Taxpayer Identification Number (ITIN) using Form W-7 (Click ITIN)
• mail in your return to the address below with Form W-7 and supporting documents attached

Option 3 - Married Filing Jointly and you claim an exemption for your NRA spouse. (your NRA spouse will be treated as a US resident alien for US tax purposes and all of your spouse's worldwide income in USD will be subject to taxable as a US citizen or resident alien. Click here for more information about

Claiming Non-Citizen Spouse and Children On Your Taxes

• leave NRA spouse's SSN blank and print a paper copy of your tax return
• attach a statement, signed by both spouses, to your joint return for the first tax year for which the choice applies (Nonresident Spouse Treated as a Resident). It should contain the following information:
•  A declaration that one spouse was a non-resident alien and the other spouse a U.S. citizen or resident alien on the last day of your tax year, and that you choose to be treated as U.S. residents for the entire tax year.
• The name, address, and identification number of each spouse.

apply for NRA spouse’s Individual Taxpayer Identification Number (ITIN) using Form W-7 (Click ITIN)

• attach a copy of your Form W-7 (along with the necessary supporting documents) to your tax return (For the supporting documents, one option is for your spouse to get a certified copy of his/her passport which will need to be included with your tax return filing. Have your NRA spouse check with his/her local embassy regarding this certified copy) Click here for IRS website ITIN - Frequently Asked Questions
• mail your tax return along with your declaration statement (if filing as married filing jointly), Form W-7 and supporting documents to the IRS. According to the IRS, because you are filing your tax return as an attachment to your (ITIN) application, you should not mail your return to the address listed in the Form 1040, 1040A or 1040EZ instructions. Instead, send your return, Form W-7 and proof of identity and foreign status documents to:
  
       Internal Revenue Service
       Austin Service Center
       ITIN Operation
       P.O. Box 149342
       Austin, TX 78714-9342 
  
  You may also apply using the services of an IRS-authorized Acceptance Agent or visit some key IRS Taxpayer Assistance Center in lieu of mailing your information to the IRS in Austin