Do I Need a New EIN After a Business Structure Change?

You need a new EIN after a business structure change only when the legal entity itself changes — when you incorporate, form or dissolve a partnership, shift an LLC’s tax classification in specific ways, or create a new taxable entity like a bankruptcy estate. Renaming the business, moving, changing owners without terminating the entity, or electing a different tax treatment usually leaves your existing number in place.¹

The IRS treats an EIN as a permanent identifier tied to one specific legal entity. So the test isn’t whether something about your business changed. It’s whether the entity itself became a different taxpayer.

When You Need a New EIN by Entity Type

Sole Proprietors

Three events force a sole proprietor to get a new EIN: incorporating the business, forming a partnership with someone else, or filing for bankruptcy.¹ Each creates a legally distinct taxpayer.

In a Chapter 7 or Chapter 11 filing, the bankruptcy estate is a separate taxable entity, and the trustee or debtor-in-possession must obtain an EIN for the estate and use it on all returns.² If the owner dies and the estate continues operating the business, the estate also needs its own EIN going forward.³

Converting a sole proprietorship to a single-member LLC does not require a new number, as long as you don’t elect corporate or S-corporation taxation and you don’t have employees or excise tax obligations.¹

Corporations

A corporation needs a new EIN in two situations: it receives a new charter from the secretary of state, or it becomes a subsidiary of another corporation.¹

In a merger where one corporation absorbs another, the surviving corporation keeps its original EIN, and the absorbed entity’s number goes dormant.⁴ The stock-versus-assets distinction matters in acquisitions. A stock purchase, where the buyer acquires ownership shares of the existing corporation, generally lets the target keep its EIN. An asset purchase, where the buyer takes the operations but not the corporate shell, typically means the buyer needs a new EIN for those operations.

Partnerships

A partnership needs a new EIN if it incorporates, if one partner takes over the business as a sole proprietor, or if the existing partnership ends and a new one begins.¹ That last scenario catches people. When a partner leaves and the remaining person continues alone, the partnership has effectively terminated, and the sole proprietorship that replaces it is a different taxpayer.

Adding a partner while the existing partnership continues does not require a new EIN. Neither does a partnership bankruptcy filing, unlike the rule for sole proprietors.¹

LLCs

LLCs are where confusion runs highest, because the IRS has no dedicated LLC tax classification. A single-member LLC defaults to sole-proprietor treatment (a “disregarded entity”). A multi-member LLC defaults to partnership treatment. What changes the EIN picture is what happens to that underlying classification.

You need a new EIN if you terminate an LLC and form a new corporation or partnership, or if a single-member LLC becomes required to file excise or employment tax returns.¹ Adding a second member to a single-member LLC shifts it from a disregarded entity to a partnership, which functions as creating a new taxpayer. The reverse causes the same issue: if a multi-member LLC drops to one owner, the partnership has terminated and the remaining owner is now running a sole proprietorship.

Several LLC changes leave the EIN alone. Converting a partnership to an LLC still classified as a partnership keeps the same number. Electing to be taxed as a corporation or S-corporation keeps the same number. And a sole proprietor’s EIN can carry over to a single-member LLC as long as no corporate election is made and there are no employees or excise tax obligations.¹

Estates and Trusts

A probate estate is a separate taxpayer from the person who died. If the estate generates more than $600 in annual income, the executor files Form 1041 under the estate’s own EIN.³ If the deceased ran a sole proprietorship, that business also needs a new EIN once the estate continues it.¹

Trust rules split by type. A revocable (living) trust generally uses the grantor’s Social Security number while the grantor is alive. Once the grantor dies, the trust becomes irrevocable, the SSN can no longer be used, and the trust must get its own EIN. An irrevocable trust holding income-producing assets needs its own EIN from the start, even while the grantor lives. A new trust created with estate funds also needs its own EIN. Appointing a successor trustee or renaming the trust does not.

Changes That Do Not Require a New EIN

Most day-to-day business changes leave your EIN untouched. Across entity types, the IRS says you keep your existing number for:

Renaming the business or adopting a “doing business as” name. Report the change on Form 8822-B.⁵
Moving your office or storefront. Report it on Form 8822-B.
A new responsible party. Report the change on Form 8822-B within 60 days.⁵
Running several sole proprietorships under one owner. The same EIN covers all of them.
Electing S-corporation or C-corporation tax treatment for an LLC.¹
Converting a partnership to an LLC that remains taxed as a partnership.
A partnership bankruptcy filing.

How to Apply If You Do Need One

Applications go through Form SS-4. The form asks for the entity’s legal name and address, the reason for applying, the expected number of employees over the next 12 months, and the primary business activity. You must also name a responsible party — the person who controls or manages the entity — and provide that individual’s SSN or ITIN.⁶ If the responsible party is a foreign person without an SSN or ITIN and not eligible for one, you enter “foreign” or “N/A” on that line.⁷

The fastest route is the IRS online application, available Monday through Friday, 7:00 a.m. to 10:00 p.m. Eastern time. You get your EIN immediately when you finish, and the IRS then mails an official CP 575 confirmation notice, which is your permanent proof of assignment for banks and tax filings.⁸ A faxed SS-4 typically gets a response within four business days. A mailed application takes about four to five weeks.⁷

Applying through the IRS is free. The FTC has warned operators of websites that charge consumers up to $300 to file this government form for them, sometimes without clearly disclosing that the IRS itself charges nothing.⁹ If the site you’re on isn’t irs.gov, you’re probably about to pay for something that’s free.

What Happens to the Old EIN

The IRS will not cancel an EIN. Once assigned, that number stays permanently linked to the entity that received it. What you can do is deactivate the account so the IRS stops expecting filings.¹⁰

File all final tax returns for the old entity first, and check the “final return” box on the applicable form — Form 1065 for partnerships, Form 1120 for C-corporations, Form 1120-S for S-corporations, and the corresponding boxes on employment tax forms 941, 944, and 940.¹¹ Then send the IRS a letter requesting deactivation, including the entity’s EIN, legal name, address, the original EIN assignment notice if you still have it, and the reason. Skipping this step doesn’t carry its own penalty, but an active EIN with no filings on record tends to generate automated notices asking where the returns are.¹⁰

What Goes Wrong If You Use the Wrong Number

Filing under an EIN that no longer matches the entity’s legal structure creates real problems. The IRS may reject the return, delay processing, or fail to credit payments to the right account. If the mismatch causes a late filing, the failure-to-file penalty runs at 5% of the unpaid tax per month, capped at 25%.¹² A separate failure-to-pay penalty of 0.5% per month runs alongside it.¹³

Employment tax mismatches are the messiest. Payroll taxes remitted under a defunct EIN may not be credited properly, which triggers notices and penalties that take months to sort out. The cleanest approach is to get the new EIN in hand before the first filing deadline under the new structure.

1
Internal Revenue Service. When to Get a New EIN
2
Internal Revenue Service. Publication 908 (2025), Bankruptcy Tax Guide
3
Internal Revenue Service. Responsibilities of an Estate Administrator
4
Internal Revenue Service. 21.7.13 Assigning Employer Identification Numbers (EINs)
5
Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party
6
Internal Revenue Service. Form SS-4 (Rev. December 2025) Application for Employer Identification Number
7
Internal Revenue Service. Instructions for Form SS-4 (12/2025)
8
Taxpayer Advocate Service. Getting an EIN
9
Federal Trade Commission. FTC Warns Operators of Websites That Charge for an Employer Identification Number
10
Internal Revenue Service. If You No Longer Need Your EIN
11
Internal Revenue Service. Closing a Business
12
Internal Revenue Service. Get the Facts About Late Filing and Late Payment Penalties
13
Internal Revenue Service. Failure to Pay Penalty