How to fill out Form SS-4 (EIN), line by line

• Start with the EIN route that matches your situation

• Lines 1–6: legal name, contact, and addresses

• Lines 7–9: responsible party, LLC details, and entity type

• Lines 10–15: reason for applying, dates, employees, and Form 944

• Lines 16–18, third-party designee, signature, and submission

• Common Form SS-4 questions

Start with the EIN route that matches your situation

Use Form SS-4 when the applicant entity does not already have an EIN but must show one on a return, statement, or other document. An EIN is for business activities; it does not replace an individual's SSN or ITIN. Before working line by line, use the form's page 2 table to match the applicant's situation to the lines it needs to complete.

Check for an existing EIN before you begin

A new name, location, hiring plan, or tax-status choice does not automatically require a new EIN. The IRS says not to apply for a new EIN when an existing entity only changes its business name, elects or follows default classification rules under Form 8832, or when an existing corporation elects or revokes S corporation status. A buyer of a going business generally cannot use the former owner's EIN unless it acquired the corporation's stock. These checks also help you answer line 18 later.

Use the page 2 situation table to identify your line set

Match both the applicant's situation and the condition in the table. An applicant seeking an EIN only for a bank account completes a shorter line set than a business that has hired employees. The table also gives separate routes for trusts, estates, pension-plan administrators, withholding agents, single-member LLCs, and S corporations. It is a map for relevant entries, not a direction for every applicant to complete every line from 1 through 18.

• Starting a new business without employees: follow the table's new-business route and listed lines.

• Hiring employees: use the employee route if the applicant does not already have an EIN.

• Changing organization type, purchasing a going business, or creating a qualifying trust: generally complete lines 1–18 as applicable.

• government form instructions

Lines 1–6: legal name, contact, and addresses

Lines 1–3: legal name, trade name, and care-of person

Line 1 is required and identifies the legal applicant. Use the name exactly as it appears on the applicable legal document: a social security card for an individual, trust instrument for a trust, partnership agreement for a partnership, or charter or organizing document for a corporation. A sole proprietor enters the individual's name—not the business name—and should not use abbreviations or nicknames. A corporation includes its entity suffix, such as Inc., Corp., or PC.

Line 2 is for a different trade or DBA name. Use the legal name from line 1 consistently on returns unless the applicant instead uses the line 2 trade name consistently. Line 3 is not another business-name field: it is for the appropriate care-of person, such as a trustee for a trust or an executor, administrator, personal representative, or other fiduciary for an estate.

Lines 4–6: mailing address versus physical location

Lines 4a–4b provide the mailing address for IRS correspondence and generally the address used on returns. If line 3 is completed, use the executor's, trustee's, or care-of person's address. For an address outside the United States or its territories, enter the city, province or state, postal code, and country name without abbreviating it. Line 6 is the county and state of the entity's primary physical location.

Use the address pair that matches the information requested.

Lines 7–9: responsible party, LLC details, and entity type

Lines 7a–7b: identify the responsible party

The responsible party is not simply the preparer or another entity in an ownership chain. It is the person who ultimately owns or controls the applicant, or who exercises ultimate effective control over the entity and its funds or assets. Enter that person's full name on line 7a and SSN or ITIN on line 7b. Except for a government entity, the responsible party must be an individual, not an entity. A government entity may use an EIN on line 7b; a person without and ineligible for an SSN or ITIN enters “foreign” or N/A.

For a trust, the responsible party is a grantor, owner, or trustor; for a decedent estate, it is the fiduciary. After the EIN is issued, use Form 8822-B to report a responsible-party change rather than filing another SS-4.

Lines 8–9: choose the entity box after answering LLC questions

If the applicant is an LLC or foreign equivalent, answer yes on line 8a, enter its number of members on line 8b, and state on line 8c whether it was organized in the United States. Answer those questions before line 9a. Line 9a requires exactly one entity-type box; it is not itself a tax-classification election.

For a domestic single-member LLC classified as disregarded, select Other and write “disregarded entity.” A domestic LLC with two or more members that accepts default partnership treatment selects Partnership. If a domestic LLC will file Form 8832 to elect association taxable as a corporation, or Form 2553 to elect S corporation status, select Corporation and write the applicable return form number: Form 1120 or Form 1120-S. A corporation also completes line 9b with its state or foreign country of incorporation.

Lines 10–15: reason for applying, dates, employees, and Form 944

Lines 10–12: state why you need the EIN and use the matching date

Line 10 requires one reason only; a selection is required, and “N/A” is not allowed. The reason should agree with the route used on page 2. Provide the requested detail—for example, the type of new business, organizational change, trust, pension plan, banking purpose, or other reason.

Line 11 is not always the formation date. Use the business starting date for a new business, acquisition date for an operating business, or the date the new ownership entity began when changing the form of ownership. A trust uses its funding date or required-EIN date; an estate uses the decedent's date of death or the date the estate was legally funded. Line 12 is the last month of the accounting or tax year. A calendar year ends December 31.

Lines 13–15: employee counts, annual Form 944, and the first payment date

On line 13, enter the highest expected number of agricultural, household, and other employees for the next 12 months. Enter zero as -0-. If no employees are expected, skip line 14. If the business has employees, line 15 is the date it began paying wages or annuities; if it does not plan to have employees, enter “N/A.” A withholding agent instead enters the date income is or will first be paid to a nonresident alien.

Line 14 is an optional request to file Form 944 annually instead of Forms 941 quarterly. It is available when expected employment-tax liability is $1,000 or less for a full calendar year and the employer wants annual filing. It does not determine whether the entity receives an EIN.

IRS general indicators for the line 14 comparison.

Lines 16–18, third-party designee, signature, and submission

Lines 16–18: describe the activity and check for a prior EIN

Check the one line 16 box that best describes the applicant's principal activity. If none fits, select Other and specify the activity. Line 17 is required and makes that broad category concrete by identifying the principal merchandise sold, construction work done, products produced, or services provided. For construction, for example, give the particular construction work rather than only construction.

Line 18 asks whether the applicant entity named on line 1—not another related business or person—previously applied for and received an EIN. If yes, enter that prior EIN. This is the form's final check against unintentionally creating another EIN for the same applicant.

Third-party designee and signature: authorize and sign only as the rules allow

The Third Party Designee section is optional. Complete it only if you want the named person to receive the newly assigned EIN and answer questions about completing Form SS-4. It does not replace the required signature: the signature area must be complete for the authorization to be valid, and the designee's authority ends when the EIN is assigned and released. If the designee's address or telephone number matches the taxpayer's, the application must be mailed or faxed.

When a signature is required, the signer depends on the applicant: the individual applicant; a corporation's president, vice president, or other principal officer; a responsible, duly authorized member or officer for a partnership, government entity, or other unincorporated organization; or a fiduciary for a trust or estate. A foreign applicant may use any duly authorized person.

Choose one official application method

• Online: recommended when the applicant has a legal residence, principal place of business, or principal office or agency in the United States or U.S. territories. The principal officer, general partner, grantor, owner, trustor, or similar person must have a valid SSN, EIN, or ITIN to use it, and the EIN can be used immediately.

• Telephone: available only to international applicants without that U.S. or territory location connection.

• Fax or mail: use the applicable IRS route for the applicant's location. A completed Form SS-4 downloaded from IRS.gov is fillable and suitable for faxing or mailing.

Common Form SS-4 questions

What if the EIN is not assigned before a return is due?

If you do not have an EIN when a return is due, write “Applied For” and the date you applied in the EIN space. Do not enter an SSN as though it were an EIN. The IRS provides separate deposit instructions when a tax deposit is due while the EIN is pending.

What if the address or responsible party changes after the EIN is issued?

Use Form 8822-B to report a later change to the entity's responsible party, address, or location. The IRS requires responsible-party changes to be reported within 60 days. This is post-issuance account maintenance, not a reason to submit another Form SS-4.

• more government form instructions

Sources and how this page was made

This guide explains the official sources listed below in plain language. Displayed amounts, limits, percentages, and timing rules come from that material.

Source revision reflected in this guide: Form: 2025; Instructions: 2025.

• Official form: Form SS-4 (Rev. December 2025) — IRS

• Official form instructions: Instructions for Form SS-4 (12/2025) | Internal Revenue Service — IRS