From ITIN to SSN: The Year Your Status Changes
A Social Security number arrives and the ITIN stops being your number that same day. There is one letter to write, and skipping it is how years of withholding quietly stop belonging to you.
Every rule on this page is cited to an IRS source, linked where it is used. Last read against those sources September 8, 2026.
The day you receive a Social Security number, stop using your ITIN and start using the SSN on everything. Then write to the IRS asking it to void the ITIN and combine your tax records — include your full name, mailing address and ITIN, a copy of your Social Security card, and a copy of your CP565 notice if you have it. Send it to Internal Revenue Service, Austin, TX 73301-0057, or take it to a local IRS office. Skip this and the IRS warns you may not get credit for wages paid and taxes withheld under the old number.
Key takeaways
- It is your job to tell them. The IRS does not connect the two numbers on its own, and it says so.
- One letter does it. There is no special form — a letter with two attachments.
- Never file with both numbers. Duplicate records are far harder to unpick than they are to avoid.
- Going forward, more credits come into reach. The Child Tax Credit, the Earned Income Tax Credit and the education credits all become possible.
- Going backward is limited.Credits requiring a number issued before the return's due date do not become available retroactively.
The first thing to do
The IRS is direct on this: when you receive a Social Security number you must use that number for tax purposes and discontinue using the ITIN. There is no transition period and no both-for-a-while arrangement.
Source: IRS — Additional ITIN information, read September 8, 2026.
The letter, and what goes in it
There is no form for this. It is a letter, and the IRS specifies what it must contain.
- Write a short letterSay that you have been assigned a Social Security number and that you want your tax records combined. That is the whole substance of it — this is not a document that rewards length.
- Include your complete name, mailing address and ITINThe name as it appears on your tax records, and the ITIN exactly as issued.
- Attach a copy of your Social Security cardA copy. Do not send the card itself.
- Attach a copy of your CP565 notice, if you have itThe CP565 is the notice that assigned your ITIN. If you cannot find it, see finding a lost ITIN— but note the IRS wording is “if available”, so a missing CP565 does not stop you sending the letter.
- Send it, or take it in personBy post to the address below, or to a local IRS office. Going in person has one real advantage: someone confirms on the spot that you have brought the right things.
Source: IRS — Additional ITIN information, read September 8, 2026.
Why this matters more than it sounds
A housekeeping letter is easy to put off. Here is what is actually sitting inside the old number.
- Wages reported under the ITIN. Every W-2 and 1099 issued against it, and the income they record.
- Tax already withheld. Money the IRS is holding on your behalf, credited to a number it no longer connects to you.
- Your filing history. The record that you filed, and what you filed.
- Any overpayment or carryforward sitting on that account.
The IRS puts the consequence plainly: if you do not notify them when you are assigned an SSN, you may not receive credit for all wages paid and taxes withheld, which could reduce the amount of any refund due. That is not a warning about paperwork tidiness. It is a warning about money you have already paid.
Source: IRS — Additional ITIN information, read September 8, 2026.
Everyone else you have to tell
The IRS letter is the important one, but it is not the only one. Anyone who issues a form with your number on it needs the new number before they issue the next form.
| Who | Why | When |
|---|---|---|
| Your employer | So the W-2 for this year carries the SSN. A W-2 issued against the old number after the merge is exactly how withholding goes missing. | Immediately — before the year-end forms are produced |
| Banks and brokers | Interest and dividend reporting has to match the number on your return. | Immediately |
| Gig platforms and clients | 1099 reporting, same reason. | Before the next 1099 is issued |
| Your tax preparer | So next year's return is not prepared against a voided number. | Before you next file |
| State tax agencies | If your state has its own identification requirements. These vary; check yours. | When you next file a state return |
What opens up, and what does not
The reason this transition is worth caring about is not administrative. It is that a Social Security number reaches things an ITIN never could.
| Can you… | With an SSN | With an ITIN | The detail that matters |
|---|---|---|---|
| File a federal tax return | Both work. This is the entire purpose of an ITIN. | ||
| Receive a federal refund you are owed | A refund is not a benefit — it is your own overpaid money coming back. | ||
| Be claimed as a spouse or dependent | An ITIN works only where the tax benefit being claimed allows it. Since 2018 the IRS will not issue one to a spouse or dependent otherwise. | ||
| Claim the Child Tax Credit | Filer and child both need an SSN valid for employment. | ||
| Claim the $500 Credit for Other Dependents | The dependent may hold an ITIN. | ||
| Claim the Earned Income Tax Credit | Stated directly on the IRS ITIN page. | ||
| Claim an education credit | Changed for tax years beginning after December 31, 2025. | ||
| Claim a tax-treaty rate on U.S. income | One of the listed reasons for applying. | ||
| Work legally in the United States | An SSN alone is not work authorization either — the authorization comes from your immigration status. But an ITIN never confers it. | ||
| Earn Social Security or Medicare credits | The IRS states an ITIN does not qualify you for Social Security benefits. | ||
| Change or support an immigration status | Neither number does this. Any service claiming otherwise is selling you something. | ||
| Serve as identification outside the tax system | The IRS says explicitly that an ITIN does not serve as identification outside the federal tax system. | ||
| Expire from non-use | An SSN never expires. An ITIN expires after three consecutive years off a tax return. |
Source: IRS — Individual taxpayer identification number (ITIN), read September 8, 2026. Credit rows cross-checked against the IRS Child Tax Credit page and P.L. 119-21.
Most concretely, on the credit side:
| Credit or deduction | Available to an ITIN filer? | Amount | Why |
|---|---|---|---|
| Child Tax CreditCHANGED | Up to $2,200 per child | You — or your spouse if you file jointly — must have a Social Security number valid for employment, and so must each qualifying child, issued before the return's due date. | |
| Credit for Other Dependents | $500 per dependent | This is the one that still works. The dependent may hold an SSN, an ITIN or an ATIN. It starts to phase out above $200,000 of adjusted gross income. | |
| Earned Income Tax Credit | — | The IRS states plainly that an ITIN does not qualify you for the Earned Income Tax Credit. Everyone on the return needs an SSN valid for employment. | |
| American Opportunity CreditCHANGED | — | New for tax years beginning after December 31, 2025: the person claiming the credit needs a Social Security number valid for work, and where the student is someone else, the student needs one too. | |
| Lifetime Learning CreditCHANGED | — | Same change, same date. An ITIN no longer supports either education credit. | |
| Child and Dependent Care Credit | Varies with expenses and income | This credit does not carry the SSN-valid-for-employment test that the Child Tax Credit does, so an ITIN filer can generally claim it if the ordinary rules are met. | |
| Itemized deductions and the standard deduction | Varies | A resident-alien ITIN filer takes the standard deduction like anyone else. A nonresident filing Form 1040-NR generally cannot, and itemizes a narrower list instead. | |
| The 2025-2028 deductions for tips, overtime, car loan interest and seniorsCHANGED | — | Each of these carries its own valid-Social-Security-number condition, so an ITIN filer cannot take them. |
Source: IRS — Education credits: AOTC and LLC, read September 9, 2026. Child Tax Credit row from the IRS Child Tax Credit page; the new-deduction rows trace to P.L. 119-21.
Can you go back and amend?
This is the question people most want a generous answer to, and the honest answer is: partly.
| What you want to do | Possible? | Why |
|---|---|---|
| Have prior-year wages and withholding credited to you | Yes | That is exactly what the merge letter achieves. The history moves to the SSN. |
| Claim the Child Tax Credit for a past year | Generally no | The credit requires a Social Security number issued before the due date of that year's return, including extensions. A number issued afterwards does not retroactively qualify the year. |
| Claim an education credit for a past year | Generally no | Same timing condition, for tax years beginning after 31 December 2025. |
| Correct an ordinary error on a past return | Yes, within the normal time limits | Amending is unaffected by the number change. The usual deadlines for claiming a refund apply. |
A worked example
April. She stops using the ITIN entirely. She gives her employer the SSN so the W-2 for the year will carry it, and she updates her bank.
April. She writes to the IRS — name, mailing address, ITIN, a copy of the Social Security card, and a copy of the CP565 she kept from years earlier. She sends it trackably to Internal Revenue Service, Austin, TX 73301-0057 and keeps a copy of everything.
Next filing season. She files under the SSN. Her six years of history now sit under that number, including the withholding from the years she worked under the ITIN.
The credits. Going forward, her household reaches the Child Tax Credit and, if income qualifies, the Earned Income Tax Credit. For the prior years, the Child Tax Credit stays out of reach: the number was not issued before those returns were due, and that condition does not bend.
What would have gone wrong without the letter. The withholding from six years of work would still be credited to a voided number, her filing history would show a gap, and the first refund she was genuinely owed would have arrived late or short — with her having to prove from her own records what the IRS could not see.
Frequently asked questions
What do I do with my ITIN after getting an SSN?
Stop using it immediately, and write to the IRS asking it to void the ITIN and combine your tax records. Include your complete name, mailing address and ITIN, with a copy of your Social Security card and a copy of your CP565 ITIN assignment notice if you have it. The IRS then associates everything previously filed under the ITIN with your SSN.
Where do I send the letter to merge my ITIN and SSN records?
The IRS gives the address as Internal Revenue Service, Austin, TX 73301-0057. You can also do this at a local IRS office rather than by post, which has the advantage that someone confirms on the spot that you have brought the right documents.
Does my ITIN filing history transfer to my SSN?
Yes, but only once you tell the IRS. The IRS voids the ITIN and associates all prior tax information filed under it with the Social Security number. Until you send that letter, the two records sit apart, and wages and withholding reported under the old number are not connected to you under the new one.
What happens if I do not tell the IRS?
The IRS warns that you may not receive credit for all wages paid and taxes withheld, which could reduce any refund due. In plain terms: money you have already paid in tax sits against a number the IRS no longer associates with you. It is your responsibility to notify them, not theirs to notice.
Can I keep using my ITIN after I get an SSN?
No. Once you receive a Social Security number you must use it for tax purposes and stop using the ITIN. Filing with both, or continuing with the old number out of habit, creates duplicate records that take considerable effort to unpick — usually discovered when a refund does not arrive.
Do credits I could not claim before become available now?
Going forward, yes. Once you hold a Social Security number valid for employment, the Child Tax Credit, the Earned Income Tax Credit and the education credits come into reach for future years, subject to the ordinary rules. Whether a past year can be revisited depends on when the number was issued relative to that year's return deadline.
Can I amend an old return now that I have an SSN?
Sometimes, but not for the credits that turn on when the number was issued. The Child Tax Credit and the education credits require a Social Security number issued before the due date of the return, including extensions. A number issued afterwards does not retroactively qualify that year, however sympathetic the circumstances.
Do I need to tell my employer and my bank too?
Yes, and promptly. Your employer needs the SSN so the W-2 for the year carries the right number, and a bank or platform reporting interest or payments needs it for the same reason. A form issued against the old number after the merge is precisely how withholding goes missing from your record.
After the change
- 2026 federal tax calculator — what the return looks like now the credits are open.
- Family Tax Credit Finder — the credits that just became available.
- W-4 withholding optimizer — worth redoing, because the credits change the right withholding.
- Life-event tax guides — other changes that move a return.
Questions on the merge itself go to the IRS: 800-829-1040 inside the United States, or 267-941-1000 from outside it (not a toll-free number).