Understanding IRS Publication 5845: Do You Need a New Employer Identification Number?

1. Introduction – What is Publication 5845?

IRS Publication 5845 is titled “Do You Need a New Employer Identification Number?” It serves as an essential, quick-reference guide published by the Internal Revenue Service to help business owners, executors, and trustees determine whether structural or legal changes require applying for a fresh nine-digit federal tax ID.

Official IRS records reflect that Publication 5845 carries a catalog revision date of July 2023, and it was officially reposted and reaffirmed in the IRS repository on May 19, 2026. This publication remains the primary reference framework used by tax professionals and IRS processing units throughout 2026 to govern Employer Identification Number (EIN) retention and reapplication rules.

An EIN acts like a Social Security number for your business or entity. Because obtaining an unnecessary number can create confusing tax records, while failing to get a needed number can trigger penalties, Publication 5845 provides clear, definitive answers for taxpayers navigating business transitions.

2. Who Should Read This Publication

Publication 5845 is designed for anyone managing or reorganizing an entity that files federal taxes. Whether you are a solo entrepreneur scaling up or an individual handling an estate, this guide applies directly to your situation.

Key readers who will benefit from this publication include:

• Sole Proprietors and Freelancers: Individuals deciding whether to incorporate, take on partners, or buy out another business.
• Partnership and LLC Members: Business owners restructuring ownership, admitting new members, or altering entity status.
• Corporate Officers: Executives executing mergers, statutory conversions, or charter revisions.
• Estate Executors and Personal Representatives: Individuals tasked with wrapping up a decedent’s affairs or operating a deceased person’s business.
• Trustees: Fiduciaries managing revocable, irrevocable, living, or testamentary trusts.

3. Key Topics Covered

The core purpose of Publication 5845 is to draw a clean line between changes that alter an entity’s legal tax identity and administrative changes that merely require an update. Rather than searching through complex tax code volumes, taxpayers receive direct guidance across several main areas:

• The rules governing sole proprietorships and unincorporated operations.
• Changes in corporate structures, charters, and statutory mergers.
• Ownership shifts and technical terminations within partnerships.
• Special classification rules for single-member and multi-member Limited Liability Companies (LLCs).
• Life-cycle events for estates, testamentary trusts, and living trusts.
• The distinction between getting a new EIN versus filing a simple notification with the IRS.

4. Detailed Breakdown of Main Concepts

The rules outlined in Publication 5845 depend on how your business or organization is categorized for federal tax purposes. Below is a detailed breakdown of how different entities are evaluated.

Sole Proprietorships

A sole proprietorship is tied directly to the individual owner. Because the individual and the business are identical under tax law, major legal reorganizations almost always require a new identifier.

You MUST get a new EIN if:

• You incorporate your business.
• You take in partners and operate as a partnership.
• You file for bankruptcy under personal or business bankruptcy provisions.
• You purchase or inherit an existing business that you operate as a sole proprietorship.

You DO NOT need a new EIN if:

• You change the business name or “Doing Business As” (DBA) name.
• You change your business location or add new operating locations.
• You operate multiple unincorporated businesses under the same individual ownership.

Corporations

Corporations exist as independent legal entities created by state law. Consequently, changing stock ownership does not automatically end the corporate entity.

You MUST get a new EIN if:

• A corporation receives a new corporate charter from the state secretary.
• You convert to a partnership or a sole proprietorship.
• A new corporation is formed after a statutory merger.
• A corporation becomes a subsidiary of another corporation or splits off through a corporate reorganization.

You DO NOT need a new EIN if:

• You change the corporate name or headquarters address.
• The corporation declares bankruptcy.
• The corporation elects S Corporation status using IRS Form 2553.
• The ownership shares are sold, traded, or transferred to different shareholders.

Partnerships

A partnership represents an association of two or more entities or individuals conducting a joint venture. Structural departures can create a new entity under tax statutes.

You MUST get a new EIN if:

• You incorporate the partnership.
• One partner buys out everyone else and operates the enterprise as a sole proprietorship.
• You terminate an existing partnership and form a brand-new entity.

You DO NOT need a new EIN if:

• The partnership changes its business trade name or address.
• New partners join or existing partners depart, provided the partnership continues operating.

Limited Liability Companies (LLCs)

The IRS does not have an exclusive tax classification called “LLC.” Instead, the IRS treats an LLC as a corporation, a partnership, or a disregarded entity depending on member count and elections.

A single-member LLC owned by an individual is normally treated as a disregarded entity (taxed as a sole proprietorship). If it hires employees or owes federal excise taxes, it must have its own EIN. Converting an existing partnership to an LLC classified as a partnership generally does not require a new EIN.

Estates and Trusts

Estates and trusts exist to manage property and protect beneficiaries. Fiduciary administration determines whether separate legal accounts are required.

You MUST get a new EIN if:

• A trust is created using funds from an estate rather than simple estate administration.
• An estate continues to operate a decedent’s sole proprietorship business.
• A revocable living trust converts into an irrevocable trust upon the grantor’s death.
• A trust changes into an estate.

You DO NOT need a new EIN if:

• The executor, personal representative, or trustee changes.
• The beneficiaries or grantors change their names or addresses.

Summary Table: Do You Need a New EIN?

Business Structure	You Need a New EIN	You Keep Your Existing EIN
Sole Proprietorship	Incorporate, add partners, buy an existing business, or file bankruptcy.	Change business trade name, change physical address, or open branch locations.
Corporation	Receive a new state charter, complete a merger creating a new firm, or drop to a partnership.	File Form 2553 for S Corp status, change name, or trade shares among owners.
Partnership	Incorporate, drop down to a sole owner, or completely dissolve and re-form.	Add or drop partners without dissolving, change trade name, or relocate.
LLC	Form a new corporation or partnership after terminating the original entity.	Change tax status from partnership to corporation, or update company address.
Trusts & Estates	A living trust becomes irrevocable, or an estate funds a separate testamentary trust.	A new trustee or administrator takes over the existing trust or estate.

5. Practical Examples or Scenarios

Examining everyday scenarios makes the guidelines of Publication 5845 easy to put into practice.

Scenario 1: The Freelancer Incorporates

Maria runs a graphic design studio as a sole proprietor using an EIN she obtained when she hired an intern. Business is booming, so she decides to formally incorporate as a C Corporation with the state. Under Publication 5845, Maria has created a completely new legal entity. She cannot keep her old sole proprietorship EIN; she must obtain a new EIN for the corporation.

Scenario 2: The S Corporation Election

David and Alex operate a standard LLC with an existing partnership EIN. To optimize self-employment taxes, they consult their accountant and decide to be taxed as an S Corporation. Because this is simply a tax classification election rather than the creation of a new legal entity, Publication 5845 clarifies that they do not need a new EIN. They continue filing under their established number.

Scenario 3: Changing a Partnership Roster

A software consultancy has three equal partners. One partner decides to retire, and the remaining two partners buy out his share and continue operating under the exact same partnership agreement. According to Publication 5845, this ownership adjustment does not require a new EIN because the fundamental partnership structure continues.

6. How This Publication Relates to Specific Forms

Publication 5845 coordinates directly with several administrative forms you will encounter when starting, altering, or maintaining a business.

• Form SS-4 (Application for Employer Identification Number): If Publication 5845 indicates that you need a new identifier, Form SS-4 is the actual document you submit online, by fax, or by mail to get your new number.
• Form 8822-B (Change of Address or Responsible Party – Business): If you do not need a new EIN—such as when your principal office moves or your responsible officer changes—the IRS requires you to report the change on Form 8822-B within 60 days.
• Form 8832 (Entity Classification Election): Used by eligible entities to choose how they will be taxed. Changing your classification under Form 8832 generally does not force you to acquire a new EIN.
• Form 2553 (Election by a Small Business Corporation): Used by corporations or LLCs electing S Corp treatment. As clarified in Publication 5845, filing Form 2553 preserves your original EIN.

7. Common Misunderstandings Clarified

Taxpayers frequently make unnecessary work for themselves by misunderstanding federal ID requirements. Here are the most common misconceptions clarified by Publication 5845:

Myth 1: “I changed my business name, so I need a brand-new tax ID.”
Reality: Changing your legal or trade name does not require a new EIN. You simply report the name change on your annual tax return or mail an official notification letter signed by a corporate officer.

Myth 2: “Electing S Corp status means I must reapply for an EIN.”
Reality: An S Corporation is a tax election, not a structural state-level entity creation. Your existing LLC or corporate EIN remains valid after your election is approved.

Myth 3: “If our corporate board replaces the CEO, we need a new EIN.”
Reality: Corporate leadership changes never warrant a new EIN. You only need to report the updated responsible party to the IRS using Form 8822-B.

Myth 4: “Replacing a trustee requires a new trust identification number.”
Reality: The trust itself is the tax-paying entity. As long as the terms and structure of the trust remain unchanged, appointing a successor trustee requires no new EIN.

8. Why This Publication Matters for Taxpayers

Managing tax identifiers properly prevents operational delays and costly administrative disputes. Obtaining an EIN when you do not need one fragments your IRS account history, which can result in misplaced estimated payments and erroneous non-filing notices.

Conversely, operating under an obsolete EIN after an entity has legally ended can invalidate employment tax returns, nullify payroll credit filings, and freeze commercial bank accounts. Publication 5845 provides taxpayers with a quick, definitive roadmap that eliminates confusion and keeps businesses fully compliant with federal standards.

9. Frequently Asked Questions

Does it cost any money to get a new EIN from the IRS?

No. The IRS issues Employer Identification Numbers completely free of charge. You can apply directly through the official IRS website and receive your number immediately upon completing the online application.

Can I cancel an EIN if I obtained one by mistake?

The IRS cannot completely delete an EIN because the number is permanently assigned to that legal record. However, you can write a letter to the IRS requesting that they close your business tax account if no returns have been filed and no taxes are owed.

Can two businesses share the same EIN?

Only if they operate under the exact same legal ownership structure, such as two separate branch locations or divisions of a single corporation. Separate legal entities, such as two distinct LLCs, must each have their own unique EIN.

If my business changes its location to a different state, do I need a new EIN?

Generally, no. Simply moving your business operations to another state does not require a new federal EIN, provided your legal entity remains intact. However, you will need to register with the new state’s tax department and file Form 8822-B with the IRS.

10. Conclusion

Navigating business transitions requires careful attention to legal structure and federal compliance. IRS Publication 5845 serves as a clear, authoritative reference, helping taxpayers identify whether corporate reorganizations, business acquisitions, or fiduciary changes necessitate a new tax identifier.

Before you fill out a new application or update your company records, review the guidelines established in Publication 5845. Knowing when to apply for a new EIN—and when to simply update your existing account—will keep your business organized, compliant, and ready for future growth.