Whether your tax ID number changes depends on which one you have. A Social Security number stays with you for life and is replaced only in narrow circumstances. An Individual Taxpayer Identification Number (ITIN) does not change either, but it can expire after three consecutive years without use and must then be renewed. An Employer Identification Number (EIN) is tied to a specific legal entity, so whenever the underlying business structure fundamentally changes, the old EIN is retired and a new one is required.
Your SSN Stays With You for Life
The Social Security Administration treats your SSN as a lifelong identifier. Marriage, divorce, a legal name change, a move, a career change — none of these trigger a new number. After a legal name change, you keep the same nine digits and simply request an updated card by filing Form SS-5 with the SSA.1Social Security Administration. How Do I Change or Correct My Name on My Social Security Number Card Numbers are not reused or reassigned after the holder dies.2Social Security Administration. Social Security History Frequently Asked Questions
Narrow Exceptions for a New SSN
The SSA will issue a brand-new number only in tightly limited situations, and the process is difficult by design so people cannot shed debts, criminal records, or other obligations by switching numbers. Even when a new SSN is granted, the SSA cross-references the old and new numbers internally so that earnings reported under either number still count toward your benefits. Only one number is active at a time.3Social Security Administration Office of the Inspector General. Cross-Referred Social Security Numbers
Situations that may qualify:
- Ongoing identity theft where your SSN continues to be misused despite credit freezes, fraud alerts, and police reports.
- Domestic violence or harassment, where a new number is part of establishing safety. Supporting documentation from law enforcement, a shelter, or a medical professional is typically required.
- Sequential digits in your number that conflict with deeply held religious beliefs — a rare exception.
In every case, the applicant must show serious ongoing harm, not inconvenience. The SSA will not issue a new number to escape bankruptcy, avoid creditors, or erase a criminal history.4Social Security Administration. The Story of the Social Security Number
ITINs Can Expire and Need Renewal
The IRS issues ITINs to people who need a federal taxpayer ID but do not qualify for an SSN, typically nonresident aliens and their dependents.5Internal Revenue Service. Individual Taxpayer Identification Number (ITIN) Unlike an SSN, an ITIN can expire.
Under the Protecting Americans from Tax Hikes (PATH) Act of 2015, an ITIN expires if it is not included on a federal tax return for three consecutive tax years. Expiration falls on the day after the return due date for the third consecutive year of non-use.6Office of the Law Revision Counsel. 26 U.S. Code 6109 – Identifying Numbers
How Renewal Works
To renew, file Form W-7 with the “Renew an existing ITIN” box checked, include your previously assigned ITIN, and submit a U.S. federal tax return with the renewal unless you qualify for a specific exception.7Internal Revenue Service. Instructions for Form W-7 Renewal reactivates your existing number rather than assigning a new one.
Filing a return with an expired ITIN can delay processing and may result in denied credits until the number is renewed.8Internal Revenue Service. How to Renew an ITIN One boundary worth knowing: a child must have an SSN, not an ITIN, to qualify for the Child Tax Credit, whether or not the ITIN is active.9Internal Revenue Service. Child Tax Credit
If you don’t want to mail original identity documents like a passport to the IRS, an IRS-authorized Certifying Acceptance Agent can verify your documents in person, return them to you immediately, and mail the completed application on your behalf.10Internal Revenue Service. ITIN Acceptance Agents
When a Business Needs a New EIN
An EIN belongs to a legal entity, not to the people who own or run the business. When the legal structure changes fundamentally, the old EIN is retired and a new one is required.11Internal Revenue Service. When to Get a New EIN
Situations that require a new EIN include:
- Incorporating a sole proprietorship or partnership. The corporation is a new legal entity separate from the individual owner’s SSN or the partnership’s old EIN.
- Receiving a new corporate charter from the secretary of state.
- Merging into an entirely new corporation.
- Creating a subsidiary, which is a separate legal entity and must have its own EIN.
- Terminating one partnership and starting another, even with overlapping partners.
Buying an Existing Business
If you buy the assets of an existing business, you generally cannot use the seller’s EIN and need your own. The one exception is acquiring a corporation by purchasing its stock, which keeps the same corporate entity and EIN intact.12Internal Revenue Service. Instructions for Form SS-4
LLC Tax Elections
A limited liability company that simply changes its tax election, such as electing to be taxed as an S corporation, does not need a new EIN. If the LLC is terminated and a new corporation or partnership is formed to replace it, the new entity does need one.11Internal Revenue Service. When to Get a New EIN
Changes That Do Not Require a New EIN
Many routine updates do not affect your EIN because the underlying legal entity has not changed. You keep the same EIN when you change your business name, your business address, or your responsible party, and when a corporation elects S corporation status.13Internal Revenue Service. Employer Identification Number Each of these still has its own reporting requirement:
- Address or responsible party changes are reported on Form 8822-B. A change in the responsible party must be reported within 60 days.14Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party – Business
- Sole proprietors report a business name change by writing to the IRS address where they file returns. Corporations and partnerships can check the name-change box on Form 1120 or Form 1065, or send a letter if the return has already been filed.15Internal Revenue Service. Business Name Change
The principle is simple. If the legal entity that owns the assets and owes the taxes has not changed, the EIN stays. If a new legal entity has been created, a new EIN is required.
Death, Estates, and Trusts
A deceased person’s SSN is not reassigned or reused.2Social Security Administration. Social Security History Frequently Asked Questions But the estate typically needs its own EIN if estate assets produce more than $600 in annual income from sources like interest, dividends, or rental income. The executor applies with Form SS-4 and files the estate’s income tax return on Form 1041.16Internal Revenue Service. Responsibilities of an Estate Administrator If the decedent operated a sole proprietorship and the estate continues to run it, the executor must obtain a separate EIN for the business itself; the decedent’s old EIN cannot be carried forward.
Bankruptcy creates a similar break. When an individual files under Chapter 7 or Chapter 11, the bankruptcy estate is a new, separate taxable entity, and the trustee or debtor-in-possession must obtain a new EIN rather than using the debtor’s SSN. This does not apply to Chapter 12 or Chapter 13 filings, where the individual continues filing personal returns.17Internal Revenue Service. Publication 908 – Bankruptcy Tax Guide
Trusts follow the same logic. A revocable living trust generally uses the grantor’s SSN during the grantor’s lifetime. When the grantor dies, the trust typically becomes irrevocable and needs its own EIN. The same rule applies when a living trust converts to a testamentary trust or is terminated by distributing property to a residual trust.12Internal Revenue Service. Instructions for Form SS-4
Penalties for Filing With the Wrong ID
Filing information returns like W-2s or 1099s with a missing or incorrect taxpayer identification number triggers per-return penalties. For returns due in 2026, the amounts are:18Internal Revenue Service. Information Return Penalties
- Filed up to 30 days late: $60 per return.
- Filed 31 days late through August 1: $130 per return.
- Filed after August 1 or not filed at all: $340 per return.
- Intentional disregard: $680 per return, with no maximum cap.
These penalties apply separately to each incorrect return, so a business filing dozens of 1099s with wrong TINs can face thousands of dollars in combined penalties. When a business changes structure through incorporation, a merger, or an asset purchase, getting the new EIN promptly and using it on every filing from that point forward is what keeps those penalties off the ledger.