What Can Someone Do With Your Tax ID Number?

If someone gets hold of your tax ID number, they can file a fraudulent tax return to steal your refund, open credit cards and loans in your name, get hired using your identity, claim unemployment or Medicaid benefits, or blend your number with fake details to build a synthetic identity for larger fraud. The damage is rarely quick to undo: IRS identity theft cases averaged 676 days to resolve as of fiscal year 2024.¹ What follows is what each type of misuse looks like, how you’d spot it, and what to do.

Filing a Fake Tax Return in Your Name

This is the most common misuse. A thief files a Form 1040 early in the season using your Social Security Number, invents wage and withholding figures, and routes the refund to an account they control. Because the IRS processes returns first-come, first-served, you usually find out only when your own return is rejected as a duplicate filing.²

Refundable credits are the main draw. The Earned Income Tax Credit can pay up to $8,231 for households with three or more qualifying children in the 2026 tax year, so fabricated W-2 numbers are often tuned to maximize it.³ Some thieves also file amended returns or claim refunds from earlier years.

When your e-file is rejected, the IRS wants you to submit a paper return with Form 14039, the Identity Theft Affidavit.⁴ The agency then opens a victim assistance case. Its stated goal is 120 days; the actual average by the end of fiscal 2024 was over 22 months.¹ Your legitimate refund is held up the whole time.

Opening Credit Cards, Loans, and Bank Accounts

Federal rules require banks to collect a taxpayer identification number from every U.S. person before opening an account.⁵ A thief with your number can meet that requirement when applying for credit cards, personal loans, or auto financing. If your credit history is strong, they can qualify for low rates and high limits, all under your name.

Checking and savings accounts are another target, used to move stolen funds. Any interest earned gets reported to the IRS under your number, creating a record of income you never received. When fraudulent accounts go unpaid, the delinquencies, collections, and hard inquiries end up on your credit report. Cleaning that up means disputing each fraudulent item with Equifax, Experian, and TransUnion. Each bureau has 30 days to investigate once it receives your dispute.⁶

Getting Hired Under Your Identity

Someone without work authorization may use a stolen number on a Form I-9 and Form W-4 to get hired. From then on, the employer’s quarterly filings and annual W-2s tie the thief’s earnings to your tax ID, and the Social Security Administration credits those wages to your record instead of the actual worker’s.

When the wages reported under your number don’t match what you filed, the IRS sends a CP2000 notice proposing extra tax on income you never earned.⁷ The IRS’s guidance to victims is direct: don’t include the fraudulent income on your return, and don’t file an amended return to add it.⁸ Respond to the CP2000 within 30 days (60 if you live outside the United States), explain that the income isn’t yours, and include Form 14039. Ignoring the notice can lead to a formal deficiency and an assessed tax bill.

The same misuse can distort your Social Security earnings record. If postings show wages higher than you actually earned, or employers you never worked for, your future benefit calculations could come out wrong. Review your Social Security Statement, and if you find errors, gather proof such as your own W-2s and pay stubs to have the record corrected.⁹

Claiming Government Benefits and Medical Care

A stolen tax ID opens the door to public benefits. Thieves file for unemployment insurance under someone else’s identity, claiming a layoff from a real or fictitious employer.¹⁰ They also use stolen numbers to apply for Medicaid and nutrition assistance, since state agencies generally require a Social Security Number on the application.¹¹

Medical identity theft carries an extra risk: the thief’s visits, diagnoses, prescriptions, and procedures get attached to your medical file. Wrong entries in that file can affect future treatment decisions. Under the HIPAA Privacy Rule you can ask a provider to amend inaccurate information, and if the provider agrees, it must make reasonable efforts to notify anyone who relied on the wrong record. A provider can also deny an amendment request if it believes the record is accurate, in which case you can submit a statement of disagreement for inclusion in the file.¹²

Building a Synthetic Identity

A more sophisticated scheme pairs a real tax ID with a fabricated name, date of birth, and address to create a hybrid persona that doesn’t match any real person. Credit bureaus often open a new file when incoming data doesn’t match existing records, so the thief can quietly build a clean credit history on the invented identity by opening small accounts and paying them off. After months or years of manufactured good behavior, they apply for large loans or credit lines and disappear with the money.

Children are especially attractive targets here. A child’s Social Security Number has no credit history attached and often goes unmonitored for years, so it can be used to apply for credit, benefits, bank accounts, loans, and utilities without anyone noticing. The fraud may not surface until the child applies for their first credit card or student loan.¹³

If the Number Belongs to a Business

Tax ID theft isn’t limited to individuals. Someone with your Employer Identification Number can file fraudulent business returns or issue fake W-2s under your company’s name. Warning signs include an e-filed return rejected because one for the same period is already on file, notices about returns your business didn’t file or W-2s it didn’t issue, or a notice tied to an EIN your organization never applied for. In those situations the IRS asks you to submit Form 14039-B, the Business Identity Theft Affidavit, which also covers trusts, estates, and tax-exempt organizations.¹⁴

Signs Your Number Is Being Used

Tax ID misuse often goes unnoticed for months. The clearest signals:

Your e-filed return is rejected because a return using your Social Security Number was already filed.
You get a CP2000 notice proposing additional tax on wages or income you don’t recognize.⁷
Your Social Security Statement shows earnings from employers you’ve never worked for.⁹
You receive a CP01A notice assigning you an Identity Protection PIN, which means the IRS has already flagged your account.¹⁵
Credit cards, loans, or collection accounts you didn’t open show up on your credit report.
Explanation-of-benefits statements list treatments or prescriptions that aren’t yours.

What to Do If Your Tax ID Is Being Used

If you find misuse, act on several fronts at once. The core steps apply whatever the type of fraud.

Start at IdentityTheft.gov

Report what happened at IdentityTheft.gov. The FTC walks you through the questions and generates a personalized recovery plan along with an official FTC Identity Theft Report, which you’ll need when disputing fraudulent accounts with creditors and bureaus.¹⁶

File Form 14039 With the IRS

For tax-related misuse, submit Form 14039. The fastest option is completing it online at irs.gov. You can also fax it toll-free to 855-807-5720 or mail it to the IRS in Fresno, California. If you’re attaching it to a paper return because your e-file was rejected, send it with the return to the address where you normally file.⁴ For an EIN, use Form 14039-B instead.¹⁴

Report to the Social Security Administration

If your SSN was stolen, report the misuse to the SSA’s Office of the Inspector General at oig.ssa.gov or by calling the fraud hotline at 1-800-269-0271, available 10 a.m. to 2 p.m. ET, Monday through Friday.¹⁷ Check your Social Security Statement for unfamiliar earnings and request corrections if needed.

Dispute Everything With the Credit Bureaus

Contact Equifax, Experian, and TransUnion to dispute any accounts or inquiries you didn’t authorize. Send disputes by certified mail with supporting documents and your FTC Identity Theft Report. Each bureau has 30 days to investigate after receiving the dispute, and both the bureau and the business that supplied the information must correct inaccurate entries for free.⁶

How to Make Misuse Harder

You don’t have to wait for fraud to show up. A few free tools cut the risk sharply.

Credit Freeze or Fraud Alert

A credit freeze (also called a security freeze) blocks anyone, including you, from opening a new account until you lift it. It’s the strongest defense against someone taking out credit in your name. When you need to apply for credit yourself, you temporarily lift the freeze and put it back afterward. A fraud alert doesn’t block access to your credit report but tells lenders to verify your identity before approving new credit. An initial fraud alert lasts one year and can be renewed. If you already have an FTC or police report from an identity theft incident, you can place an extended alert lasting seven years. Freezes and fraud alerts are free.¹⁸

IRS Identity Protection PIN

The IRS issues a six-digit Identity Protection PIN that you include on your tax return each year. Any return filed under your Social Security Number without the correct IP PIN gets rejected. Anyone with an SSN or ITIN can request one; you don’t need to have been a victim. The fastest path is enrolling through your online IRS account. If you can’t verify online and your adjusted gross income is below $84,000 ($168,000 for married filing jointly), you can apply with Form 15227 and verify by phone, with the PIN mailed to you in four to six weeks. You can also book an in-person appointment at a Taxpayer Assistance Center, after which the PIN arrives in about three weeks.¹⁹

Everyday Habits

Basic habits cut your exposure. Shred documents that contain your tax ID before throwing them out. Don’t carry your Social Security card in your wallet. Push back when businesses ask for your number; many that request it don’t legally require it. Review your Social Security Statement each year for unfamiliar earnings, and check your credit reports regularly for accounts you didn’t open. If your number was exposed in a breach but hasn’t yet been misused, the SSA points to IdentityTheft.gov/Info-Lost-or-Stolen for steps to take before any fraud occurs.¹⁷

1
Taxpayer Advocate Service. Identity Theft – Processing and Refund Delays Are Harming Victims of Tax-Related Identity Theft
2
Internal Revenue Service. Instructions for Requesting Copy of Fraudulent Returns
3
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
4
Internal Revenue Service. Form 14039 – Identity Theft Affidavit
5
eCFR. 31 CFR 1020.220 – Customer Identification Program
6
Consumer Advice – FTC. Disputing Errors on Your Credit Reports
7
Internal Revenue Service. Topic No. 652 – Notice of Underreported Income CP2000
8
Internal Revenue Service. Guide to Employment-Related Identity Theft
9
Social Security Administration. How to Correct Your Social Security Earnings Record
10
USAGov. Unemployment Benefits
11
USAGov. How to Apply for Medicaid and CHIP
12
HHS.gov. Summary of the HIPAA Privacy Rule
13
Consumer Advice – FTC. How to Protect Your Child From Identity Theft
14
Internal Revenue Service. Report Identity Theft for a Business
15
Internal Revenue Service. Notice CP01A
16
Federal Trade Commission. IdentityTheft.gov
17
Social Security Administration. Fraud Prevention and Reporting
18
Consumer Advice – FTC. Credit Freezes and Fraud Alerts
19
Internal Revenue Service. Get an Identity Protection PIN