I had used my wife's ITIN as the IRS did not figure out her SSN that she got after she started using ITIN. Now she has income with her SSN. Which number have I to use?

[teddy839]

In her basic information, I put her ITIN but had to use her SSN in her income section as her W-2 form has her SSN information. So have I to keep these two numbers (ITIN in the basic information section and SSN in the income section) or use her SSN even in the basic information section?

[Opus 17 · Accepted solution]

When an SSN is assigned you must always use it from then on.  Separately, you send a letter to the IRS notifying them of the SSN so they can link her records. 

What do I do when I am assigned a social security number (SSN)?

Once you receive a SSN, you must use that number for tax purposes and discontinue using your ITIN.  It is improper to use both the ITIN and the SSN assigned to the same person to file tax returns.  It is your responsibility to notify the IRS so we can combine all of your tax records under one identification number.  If you do not notify the IRS when you are assigned a SSN, you may not receive credit for all wages paid and taxes withheld which could reduce the amount of any refund due.  You can visit a local IRS office or write a letter explaining that you have now been assigned a SSN and want your tax records combined.  Include your complete name, mailing address, and ITIN along with a copy of your social security card and a copy of the CP 565, Notice of ITIN Assignment, if available.  The IRS will void the ITIN and associate all prior tax information filed under the ITIN with the SSN.  Send your letter to: 

     Internal Revenue Service 
     Austin, TX 73301-0057