Employer Identification Number (EIN): What It Means for Employers

What it means in practice

What the number is. Treasury regulation 26 CFR 301.6109-1 says EINs "are used to identify employers" and that any person other than an individual, such as a corporation, partnership, trust or estate, must use an EIN when it has to furnish a number; an individual who is an employer or sole proprietor should use one as forms and instructions require. Publication 15 (2026) tells employers to use the EIN on all items sent to the IRS and the Social Security Administration. The taxpayer identification number (TIN) entry compares the EIN with other kinds of TIN.

Who needs one. The IRS Employer ID Numbers page says you need an EIN if you have employees, pay employment, excise or alcohol, tobacco and firearms taxes, or withhold tax on non-wage income paid to a nonresident alien. Partnerships, LLCs, corporations, tax-exempt organizations, estates, most trusts and retirement plans also need one. Publication 15 puts the employer rule plainly: if you must report employment taxes or give tax statements to employees or annuitants, you need an EIN. An entity may also request one for banking or state tax purposes.

Who usually does not. Form SS-4 page 2 says a sole proprietor needs an EIN once it hires employees, sets up a qualified retirement plan, or must file excise, employment, alcohol, tobacco or firearms returns. Under 26 CFR 301.6109-1(h), a single-owner entity disregarded for federal tax purposes generally uses its owner's TIN, but Publication 15 says eligible disregarded entities and qualified subchapter S subsidiaries are treated as separate entities for employment tax purposes and must report and pay employment taxes under their own names and EINs.

Key definitions. (1) Responsible party. The SS-4 instructions define this as the person who ultimately owns or controls the entity, or exercises ultimate effective control over it and its funds and assets. Except for government entities, it must be an individual: usually a corporation's principal officer, a partnership's general partner, a trust's grantor or trustee, or an estate's executor. (2) Nominee. Someone given limited authority to act during formation; the IRS says a nominee cannot apply for an EIN and should not be listed on Form SS-4. (3) Third-party designee. A person the applicant authorizes, in the signed designee section of Form SS-4, to answer questions and receive the new EIN; that authority ends when the EIN is assigned.

Before applying. The IRS says a legal entity such as an LLC, partnership or corporation should be registered with its state first; applying before the entity is formed may delay the application. Line 1 of Form SS-4 takes the legal name exactly as it appears on the charter or other legal document, and line 2 any "doing business as" name. IRS systems accept only letters, numbers, hyphens and ampersands in business names, and street addresses are limited to 35 characters (IRS Employer ID Numbers page).

Applying online. The online application is for organizations formed in the U.S. or U.S. territories with a principal place of business there, completed by the responsible party or an authorized representative with the responsible party's SSN or ITIN. It must be finished in one session, expires after 15 minutes of inactivity, and issues the EIN immediately if approved. The IRS lists its hours (Eastern time) as 6 a.m. to 1 a.m. the next day on weekdays, 6 a.m. to 9 p.m. Saturday, and 6 p.m. to midnight Sunday.

Applying by fax, mail or phone. Under the SS-4 instructions (Rev. December 2025), applicants in the 50 states or the District of Columbia can fax Form SS-4 to 855-641-6935 and generally receive the EIN within 4 business days, or mail it to the IRS EIN Operation in Cincinnati at least 4 to 5 weeks before the number is needed. The IRS no longer issues EINs by phone to domestic applicants. The instructions say to use only one method per entity so it does not receive two EINs.

Lines that matter to employers. On line 10, "Hired employees" is the reason for an existing business that must now file employment tax returns, but the instructions say not to apply if the business already has an EIN and is only hiring. Line 13 asks for the highest number of agricultural, household and other employees expected in the next 12 months. Line 14 is the election to file Form 944 annually instead of Form 941 quarterly; the instructions say liability will generally be $1,000 or less if wages subject to Social Security, Medicare and income tax withholding are $5,000 or less, and a checked box keeps the employer on Form 944 until the IRS says otherwise. Line 15 is the first date wages were or will be paid.

When the number can be used. The IRS says a new EIN can be used immediately to open a bank account, apply for business licenses or file a return by mail, but it can take up to 2 weeks before it passes IRS TIN Matching or works for e-filing and electronic tax deposits. Publication 15 says a new employer that showed a federal tax obligation when applying is pre-enrolled in EFTPS. If a return is due before the EIN arrives, it says to file a paper return with "Applied For" and the application date in place of the number. Deposit rules are covered under federal tax deposit.

Using it on payroll filings. Publication 15 says the EIN on every form must exactly match the one the IRS assigned, and an SSN or ITIN must not go on forms that ask for an EIN. The 2026 General Instructions for Forms W-2 and W-3 say box b of Form W-2 shows the same EIN used on the employment tax returns, untruncated and never a prior owner's; Form W-3 box h reports any other EIN used on that year's Forms 941, 943, 944 or CT-1. Payees ask for the EIN on Form W-9, and it appears on Form 1099 filings and the Form 940 FUTA return.

One entity, one EIN. The IRS says a business entity should have only one EIN, and the SS-4 instructions say a sole proprietor generally needs only one, however many businesses or trade names it runs, although each corporation in an affiliated group needs its own. An employer holding more than one EIN can call the Business and Specialty Tax Line at 800-829-4933 with the numbers, the name and address each was assigned to, and its main business address, and the IRS will say which to use (Publication 15).

When a new EIN is needed. The IRS page "Do you need a new EIN?" says a new number is generally needed when ownership or structure changes. Its examples include a sole proprietor who incorporates, forms a partnership or declares bankruptcy; a corporation that gets a new charter, becomes a subsidiary, converts to a partnership or sole proprietorship, or merges into a new corporation; a partnership that incorporates; and a single-member LLC that has to file employment or excise taxes. A buyer of a going business uses its own EIN, not the former owner's, unless it acquired a corporation's stock (Instructions for Form SS-4).

When it is not. The same page says a name or location change, an S corporation election, a surviving corporation after a merger, a division of a corporation, and an LLC changing its tax election all keep the existing EIN. Under 26 CFR 301.6109-1(h), an entity keeps its EIN when its federal tax classification changes.

Keeping the record current. Publication 15 says to notify the IRS immediately of a business name change by writing to the IRS office where returns are filed; the IRS Business Name Change page adds that corporations and partnerships filing a current-year return can check the name change box on Form 1120, 1120-S or 1065. Address, location and responsible party changes go on Form 8822-B, and a responsible party change must be reported within 60 days.

Lost numbers, confirmations and misuse. To find a missing EIN, the IRS suggests the assignment notice, the business bank, state or local licensing agencies, past returns, or a call to 800-829-4933. Proof of the number by notice, transcript or Letter 147C is covered in the CP 575 letter entry. For an EIN no one requested, the IRS points to Form 14039-B, Business Identity Theft Affidavit.

Closing the account. The IRS calls the EIN the permanent federal taxpayer identification number for a business. To close the account it asks for a letter with the legal name, EIN, address and reason, plus a copy of the assignment notice if available, and it will not close the account until all required returns are filed and taxes paid, which for employers includes final employment tax returns and Forms W-2 (IRS, Closing a business).

Where states differ. The federal EIN does not replace state employer registration. As an example only, California's Employment Development Department says a business must register as an employer within 15 days after paying more than $100 in wages in a calendar quarter, asks for the federal EIN on the registration, and then issues a separate eight-digit State Employer Identification Number for state payroll returns, wage reports and payments. Other states set their own thresholds and numbers; see SUTA.

Example 1 (illustration): the seven-day rule. A new corporation with no EIN pays its first wages on Monday, March 2, 2026. Under 26 CFR 31.6011(b)-1(a)(2), Form SS-4 is to be filed on or before the seventh day after that payment, Monday, March 9, 2026. Since e-filing and electronic deposits may not work for up to 2 weeks after assignment (IRS), applying before the first payroll avoids a gap.

Example 2 (illustration): single-member LLC hires. An LLC owned by one individual reports its income on the owner's Schedule C and has no EIN. Once it hires an employee, the IRS "Do you need a new EIN?" page and Publication 15 say it needs its own EIN for employment taxes, even though it stays disregarded for income tax.

Example 3 (illustration): new responsible party. A company's principal officer, listed as responsible party, is replaced effective June 1, 2026. Counting 60 days from that date gives Friday, July 31, 2026 as the end of the window to file Form 8822-B. The EIN itself does not change.

Recordkeeping. The IRS asks for a copy of the assignment notice when closing an account, and Publication 15 says to keep employment tax records for at least 4 years.

Question: Does hiring a payroll provider change my EIN? No. The IRS third-party arrangement chart says payroll service providers and reporting agents file separate returns under each client's EIN, while section 3504 agents and CPEOs file aggregate returns under their own; see payroll service.

Question: Can I use my SSN instead? Not on forms that ask for an EIN, under Publication 15 and the SS-4 instructions; see Social Security number.

Question: Do I need a new EIN after buying a business? Generally yes, unless you acquired a corporation's stock. The IRS says not to use the prior employer's EIN to report and deposit employment taxes.

This entry describes how the EIN works under federal rules and does not decide whether a particular entity needs one or which number it should use.

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