An ITIN and an SSN are both nine-digit tax identifiers, but only one of them lets you work, build Social Security credits, and claim the largest federal tax credits. The Social Security Number goes to U.S. citizens, permanent residents, and noncitizens with work authorization from the Department of Homeland Security. The Individual Taxpayer Identification Number exists for people who have a federal tax filing obligation but can’t get an SSN. If your immigration status changes and you become eligible for an SSN, you’re expected to stop using the ITIN and ask the IRS to combine the two records. That switch can be worth thousands of dollars a year in tax credits alone.
How to Tell Which Number You Have
Both numbers use the XXX-XX-XXXX format, so the giveaway is the first digit. SSNs start with 001 through 899, skipping 666. ITINs always start with a 9. If you see a nine-digit number on a W-2 or 1099 that begins with 9, that’s an ITIN.
Who Qualifies for Each One
SSNs are issued by the Social Security Administration to U.S. citizens, lawful permanent residents, and noncitizens who have DHS work authorization. You apply on Form SS-5 at a local SSA field office and submit proof of age, identity, and citizenship or immigration status.1eCFR. 20 CFR Part 422 – Organization and Procedures Once the SSA has what it needs, cards typically arrive in 7 to 10 business days.2Social Security Administration. How Long Will It Take to Get a Social Security Card?
ITINs come from the IRS and are for people who need to file a U.S. federal tax return but don’t qualify for an SSN. That covers nonresident and resident aliens, along with spouses and dependents who need a taxpayer identification number for reporting.3Legal Information Institute. 26 USC 6109 You apply on Form W-7, either by mail to the IRS or through a Certified Acceptance Agent who can authenticate your documents in person and return the originals to you immediately.4Internal Revenue Service. ITIN Acceptance Agents
What Each Number Lets You Do
An SSN opens the door to legal employment, wage reporting that builds your Social Security record, credit applications, and government programs that require the number. Your employer reports your wages to the SSA under your SSN, and those earnings determine future eligibility for retirement, disability, and survivor benefits.5Social Security Administration. Employer W-2 Filing Instructions and Information – Critical Links
An ITIN does one thing: it lets you file a federal tax return. It does not authorize employment, change your immigration status, qualify you for Social Security benefits, or work as general identification.6Internal Revenue Service. Individual Taxpayer Identification Number (ITIN) You cannot use an ITIN on Form I-9 to verify work eligibility. Many banks will accept an ITIN in place of an SSN to open an account, though you’ll usually need to go in person because most online applications require an SSN.
Not All Social Security Cards Are the Same
The SSA issues three versions of the card, and the type you receive matters:
- An unrestricted card shows your name and SSN with no legend and goes to U.S. citizens and lawful permanent residents. It lets you work without limitation.
- A work-restricted card is printed with “VALID FOR WORK ONLY WITH DHS AUTHORIZATION” and goes to people admitted temporarily who have DHS work authorization.
- A non-employment card is printed with “NOT VALID FOR EMPLOYMENT” and goes to people lawfully present without work authorization who need the number for a non-work reason.7Social Security Administration. Types of Social Security Cards
The legend on the card also affects tax credits. A card marked “NOT VALID FOR EMPLOYMENT” will not satisfy the SSN requirement for the Earned Income Tax Credit even after you gain work authorization, until you get a replacement card without that legend.8Internal Revenue Service. Who Qualifies for the Earned Income Tax Credit (EITC)
Tax Credits You Gain by Moving to an SSN
This is where the difference hits your bank account. Two of the largest federal tax credits are simply not available to ITIN filers.
Earned Income Tax Credit
The EITC requires a valid, work-authorized SSN for the taxpayer, the spouse on a joint return, and every qualifying child. An ITIN will not work. For tax year 2025, the maximum credit is $8,046 for families with three or more qualifying children, $7,152 for two, $4,328 for one, and $649 for workers with no qualifying children.9Internal Revenue Service. Earned Income and Earned Income Tax Credit (EITC) Tables The SSN must be issued on or before the due date of the return, including extensions.
Child Tax Credit
The Child Tax Credit is worth up to $2,200 per qualifying child, with a refundable Additional Child Tax Credit of up to $1,700 per child for families with little or no federal income tax liability.10Internal Revenue Service. Child Tax Credit Both the taxpayer and the qualifying child must have SSNs valid for employment, issued before the return’s due date. A child with only an ITIN cannot be claimed for either the CTC or the Additional CTC.11Internal Revenue Service. Child Tax Credit FAQ
For a family with three children moving from ITINs to SSNs, the combined value of the EITC and Child Tax Credit alone can exceed $14,000 in a single tax year. That’s the strongest practical reason to make the transition as soon as you qualify.
ITINs Can Expire
If your ITIN goes unused on a federal tax return for three consecutive tax years, it expires on December 31 after that third year of non-use.12Internal Revenue Service. How to Renew an ITIN Being listed as a dependent on someone else’s return counts as use, so you don’t necessarily start the clock just because you didn’t file your own.
To renew, submit a new Form W-7 with the “Renew an existing ITIN” box checked. Filing with an expired ITIN can delay your refund, reduce it, or trigger penalties and interest. Include supporting documents like a marriage certificate or court order if your legal name has changed since the ITIN was issued.
You do not need to renew an expired ITIN if you’ve obtained an SSN. And if your ITIN appears only on information returns like a 1099 that someone else files to report payments to you, an expired ITIN can still be used on those documents.
Transitioning From an ITIN to an SSN
Once you have status that qualifies you for an SSN, complete Form SS-5 and visit a local SSA field office. Noncitizens need a current, unexpired DHS document showing status, such as a Permanent Resident Card (Form I-551), an I-94 arrival record, or an Employment Authorization Document (Form I-766), plus a foreign passport.13Social Security Administration. Form SS-5 – Application for a Social Security Card If you’re adjusting status through USCIS on Form I-485 or Form I-765, the SSA generally issues the card within 7 to 10 business days after USCIS approves your application.
Once the SSN arrives, stop using the ITIN. Using both numbers at the same time is improper, and if you keep filing under the ITIN after receiving an SSN, the IRS may not credit all your wages and withheld taxes to the correct account, which can shrink your refund.14Internal Revenue Service. Additional ITIN Information
Merging Your Old Tax Records With the New SSN
Getting the SSN is only half the job. You also need to tell the IRS to combine your old ITIN records with the new SSN so prior filings, payments, and withholding credits all appear under one identity. Write a letter to the IRS with your full legal name, current mailing address, your ITIN, and your new SSN, and ask them explicitly to merge the records. Include a copy of your new Social Security card and, if you have it, the original ITIN assignment letter.
Send the letter to:
Internal Revenue Service
Austin, TX 73301-0057
This is not the same address used for ITIN applications and name changes, so double-check before mailing.6Internal Revenue Service. Individual Taxpayer Identification Number (ITIN) Gather all previous tax records filed under the ITIN before writing so you can verify later that every year was transferred. Keep copies of everything you send, and check your IRS account periodically to confirm prior-year data appears under your SSN. You do not need to file amended returns for prior years filed under the ITIN; the notification letter is how the IRS links the two records.
Updating Your Employer and Financial Institutions
Give your new SSN to your employer’s payroll department as soon as your card arrives. Employers report wages to the SSA on Form W-2 each year, and the SSA matches the name and SSN on each W-2 against its database to post earnings to your record. Those earnings determine your future eligibility for retirement, disability, and survivor benefits.5Social Security Administration. Employer W-2 Filing Instructions and Information – Critical Links If your employer already filed a W-2 under your ITIN for the current year, they should submit a corrected Form W-2C with your new SSN.
Also update the number with any bank, brokerage, or payer that has your ITIN on file for tax reporting. These institutions report interest and investment income to the IRS under your taxpayer identification number, and mismatched numbers can trigger IRS notices or delay processing of your return.