A tax ID number is a nine-digit code the IRS uses to identify you or your business on tax returns, information reports, and related paperwork. Federal law requires one on every return filed and every income item reported.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers Most people already have one in the form of a Social Security number, but the IRS issues four other types for situations the SSN doesn’t cover: businesses, non-resident filers, adoptive parents waiting on a child’s SSN, and paid tax preparers. Picking the right one is the whole game, because using the wrong number on a form is one of the fastest ways to have a return rejected or an account application stall.
The Five Types and Who Needs Each
The IRS recognizes five tax identification numbers. Each belongs to a specific category of taxpayer.
Social Security Number (SSN)
The Social Security Administration issues the SSN to U.S. citizens, permanent residents, and certain temporary residents authorized to work. It tracks your lifetime earnings for benefit purposes and serves as your identifier on personal tax returns.2Internal Revenue Service. Taxpayer Identification Numbers (TIN) Employers ask for it at hiring and use it on your W-2.3Internal Revenue Service. Hiring Employees Banks and lenders rely on it too, because credit bureaus tie your borrowing history to it.
Employer Identification Number (EIN)
An EIN identifies a business or organization rather than a person. You need one if you hire employees, operate as a partnership or corporation, pay excise taxes, or administer certain trusts, estates, or retirement plans.4Internal Revenue Service. Get an Employer Identification Number Banks also require one to open a business account. Sole proprietors with no employees can usually use their SSN, but many still get an EIN to keep the personal number off business paperwork.
Individual Taxpayer Identification Number (ITIN)
If you have a federal tax filing obligation but can’t get an SSN, the ITIN fills that gap. It applies most often to non-resident aliens with U.S.-source income and to dependents or spouses claimed on someone else’s return who aren’t SSN-eligible.5Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
The limits matter. An ITIN does not authorize you to work in the United States, does not affect immigration status, and does not qualify you for Social Security benefits or the Earned Income Tax Credit. Employers cannot accept it in place of an SSN for employment verification.3Internal Revenue Service. Hiring Employees It exists for federal tax purposes and nothing else.
Adoption Taxpayer Identification Number (ATIN)
The ATIN is a temporary placeholder for a child being adopted domestically or internationally when the adoptive parents can’t obtain the child’s existing SSN or get a new one before the adoption finalizes. It lets parents claim the child as a dependent in the meantime. Once the child receives a permanent SSN, the IRS deactivates the ATIN. If the adoption stalls, the number automatically deactivates after two years.
Preparer Tax Identification Number (PTIN)
Anyone who prepares federal tax returns for compensation must have a PTIN and include it on every return they file. A preparer who leaves it off faces a penalty with a statutory base of $50 per return and a calendar-year cap of $25,000, both adjusted annually for inflation.6Office of the Law Revision Counsel. 26 USC 6695 – Other Assessable Penalties With Respect to the Preparation of Tax Returns for Other Persons
How to Get an EIN
The IRS issues EINs for free. That’s worth stating plainly, because third-party sites routinely charge up to $300 to file the application for you, some of them designed to look like the IRS itself. The FTC has warned these operators that impersonating a government agency can result in civil penalties.7Federal Trade Commission. FTC Warns Operators of Websites That Charge for Employer Identification Number Claim Affiliation With IRS Apply directly at IRS.gov.
The online EIN Assistant is the fastest route and gives you the number on screen as soon as the application is approved.4Internal Revenue Service. Get an Employer Identification Number Have these ready before you start:
- The exact legal name of the entity as it appears on its charter or formation documents.
- The name and SSN, ITIN, or existing EIN of the responsible party (the principal officer of a corporation, a general partner of a partnership, or the owner of an LLC).8Internal Revenue Service. Instructions for Form SS-4
- The entity type: corporation, LLC, partnership, sole proprietorship, trust, or estate.
- The principal business address, plus a mailing address if different.
If you can’t apply online, fax Form SS-4 to 855-641-6935 and you’ll receive the EIN by fax in about four business days. Mailing the form to the IRS in Cincinnati, OH 45999 takes about four weeks.9Internal Revenue Service. Employer Identification Number
How to Get an ITIN
There is no online ITIN application. You complete Form W-7 and mail it to the IRS Austin Service Center along with your federal tax return, unless you qualify for one of the specific exceptions the instructions list.10Internal Revenue Service. How to Apply for an ITIN You also have to submit original identity documents or copies certified by the issuing agency.11Internal Revenue Service. Instructions for Form W-7
A valid passport is the simplest option because it proves both identity and foreign status by itself. Without one, you’ll need at least two documents from the IRS’s approved list to cover both requirements.
Mailing your passport understandably makes people uneasy. Two alternatives let you keep the originals in hand:
- A Taxpayer Assistance Center that offers ITIN services can review your Form W-7, authenticate most documents in person, and return them at your appointment before forwarding the package to the IRS.10Internal Revenue Service. How to Apply for an ITIN
- A Certified Acceptance Agent, approved by the IRS, authenticates your documents, returns them immediately, and mails the application on your behalf.12Internal Revenue Service. ITIN Acceptance Agents
Processing usually takes about seven weeks. Between January 15 and April 30, or if you apply from outside the country, expect nine to eleven weeks. The IRS mails a formal notice with your number once you’re approved.
Renewing an ITIN or Getting a New EIN
An ITIN expires on December 31 of the third consecutive year you don’t use it on a federal tax return.13Internal Revenue Service. How to Renew an ITIN You can still receive information returns like a 1099 on an expired ITIN, but you can’t file a return with it until you renew. Renewal uses the same Form W-7. Check the “Renew an existing ITIN” box, enter the number on lines 6e and 6f, and attach documentation for any legal name change since the ITIN was issued.
An EIN, by contrast, stays with a business permanently. Changing your business name or address does not require a new one.14Internal Revenue Service. When to Get a New EIN Structural changes usually do. Common triggers include a sole proprietor incorporating or forming a partnership, a corporation receiving a new charter or merging into a new entity, a partnership incorporating or dissolving into a sole proprietorship, an LLC terminating to become a corporation or partnership, and a revocable trust becoming irrevocable. The IRS publishes a full breakdown by entity type if your situation doesn’t fit neatly.
If You’ve Lost the Number
Recovering a misplaced tax ID is usually quick.
For a lost EIN, check the original IRS confirmation notice first. If it’s gone, look at a past business return, a state or local license application, or your business bank account records. If none of those turn it up, call the IRS Business and Specialty Tax Line at 800-829-4933 (weekdays, 7:00 a.m. to 7:00 p.m. local time). Once you verify your identity, the IRS will give the number over the phone or send a Letter 147C confirming it.9Internal Revenue Service. Employer Identification Number
For a lost SSN, you rarely need the physical card since institutions just need the number. If you do need a replacement card, many people can request one through the Social Security Administration’s online service; otherwise, call 800-772-1213 or make an appointment at a local SSA office. Replacement cards arrive in five to ten business days.15Social Security Administration. Replace Social Security Card
Protecting Your Number From Fraud
Your SSN or ITIN unlocks tax filings, credit accounts, and bank accounts, which makes it a target. The strongest defense the IRS offers is the Identity Protection PIN: a six-digit number issued annually that has to appear on your return. If someone tries to file with your SSN or ITIN and doesn’t have the PIN, the return is rejected.16Internal Revenue Service. Frequently Asked Questions About the Identity Protection Personal Identification Number (IP PIN)
Anyone with an SSN or ITIN can enroll by verifying their identity through an IRS Online Account. If online verification fails and your adjusted gross income is below $84,000 ($168,000 for married filing jointly), you can submit Form 15227. Otherwise you can enroll in person at a Taxpayer Assistance Center with identity documents.
Basic habits help too. Don’t carry your Social Security card in your wallet, don’t share the number without confirming why the requester needs it, and check your IRS account periodically for filings you don’t recognize. If a fraudulent return has already been filed under your number, report it with Form 14039, Identity Theft Affidavit.