Registry entry

United States Employer Identification Number Application (Form SS-4)

Apply for an Employer Identification Number (EIN), the 9-digit federal tax identifier the IRS assigns to a business entity, using the data model of IRS Form SS-4 (Application for Employer Identification Number). Covers a single-member LLC, sole proprietorship, corporation, partnership, trust, estate, or nonprofit applying for its first EIN. The fastest channel is the IRS EIN online assistant (immediate issuance), available only to applicants whose principal business is in the U.S. or a U.S. territory and whose responsible party has an SSN or ITIN; applicants outside that scope must apply by fax, mail, or (international applicants only) telephone, using this same Form SS-4 field set. It does not submit the application; the live IRS source is always authoritative (see VERIFICATION.md).

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The latest published version of this schema is v2.3.0 — see the current reference page. Published versions are immutable; this page stays for agents pinned to us/irs/employer-identification-number-ss4@1.0.0.

Registry entry

us/irs/employer-identification-number-ss4

Jurisdiction
United States · national
Version
1.0.0
Verification
draft
Authority
Internal Revenue Service

GovSchema spec v0.1

Authoritative source Form SS-4 (Rev. December 2025)

Machine access

Schema document
registry/us/irs/employer-identification-number-ss4/1.0.0/schema.jsonapplication/schema+json
Verification record
registry/us/irs/employer-identification-number-ss4/1.0.0/VERIFICATION.mdtext/markdown
Registry catalog
registry/index.jsonone record per schema id

Field reference

49 fields across 11 steps, read from the published schema.json — names, types, requiredness, and validation as the document states them. The live government form remains the authoritative source.

Entity name

  • entityLegalName string required

    Personal/business identifier; handle as sensitive data. The legal name of the business, trust, estate, or individual applying — e.g. as it appears on the entity's formation document, or an individual's legal name for a sole proprietorship.

    length: 1–160
  • tradeName string optional

    The 'doing business as' (DBA) name, if different from the legal name.

    length: 0–160
  • careOfName string optional

    Personal identifier; handle as sensitive data. Required when the applicant entity is an estate or trust and correspondence should be directed to a named executor, administrator, or trustee.

    length: 0–160

Mailing and principal addresses

  • mailingAddressLine1 string required

    Where the IRS will send the EIN confirmation notice (CP 575) and correspondence. A P.O. box is allowed here, unlike the principal (street) address.

    length: 1–120
  • mailingAddressCity string required

    If foreign, the instructions give a different city/province/postal-code format; see mailingAddressCountry.

    length: 1–80
  • mailingAddressState string optional

    Two-letter USPS state or territory abbreviation, e.g. CA, NY, TX. Not applicable to a foreign address; see mailingAddressCountry instead.

    pattern
  • mailingAddressPostalCode string optional

    5-digit or ZIP+4 U.S. format, e.g. 90210 or 90210-1234. For a foreign address, give the foreign postal code here instead, per the instructions.

    length: 0–15
  • mailingAddressCountry string optional

    Required only when the mailing address is outside the United States; see the Form SS-4 instructions for the foreign address format.

    length: 0–100
  • principalAddressLine1 string optional

    The entity's actual physical/principal business location. Cannot be a P.O. box, unlike the mailing address.

    length: 0–120
  • principalAddressCity string optional

    Required only when principalAddressLine1 is given.

    length: 0–80
  • principalAddressState string optional

    Two-letter USPS state or territory abbreviation. Required only when principalAddressLine1 is a U.S. address.

    pattern
  • principalAddressPostalCode string optional

    Required only when principalAddressLine1 is given.

    length: 0–15
  • principalBusinessCountyAndState string optional

    Free-text county name and state, e.g. "Orange County, CA". Not applicable to every reason for applying (e.g. not needed for a banking-purpose-only application); see reasonForApplying.

    length: 0–120

Responsible party

  • responsiblePartyName string required

    Personal identifier; handle as sensitive data. The person who ultimately owns or controls the entity, or who exercises ultimate effective control. Per the Form SS-4 instructions, the responsible party must be an individual (a natural person), not an entity, except where the applicant itself is a government entity. Required on every EIN application regardless of reason for applying.

    length: 1–160
  • responsiblePartyTaxId string required

    Personal identifier; handle as sensitive data. 9 digits, no separators. The IRS online EIN assistant additionally requires this to be an SSN or ITIN (not an EIN) and requires the responsible party themselves to be the applicant or their authorized representative.

    pattern

Limited liability company details

  • isLLC boolean optional

    Required for most applicants, but not on every path: the Form SS-4 "Do I Need an EIN?" table (page 2) excludes line 8a from the lines to complete for a plan administrator, an estate administrator, or a state/local tax-reporting agency. If true, also give llcMemberCount and llcOrganizedInUS, and see the instructions for the correct entityType box.

  • llcMemberCount integer optional

    Required only when isLLC is true.

    range: 1–∞
  • llcOrganizedInUS boolean optional

    Required only when isLLC is true.

Type of entity

  • entityType enum required

    Check only one box. If isLLC is true, see the instructions for which box applies to the LLC (an LLC is not itself a box; it is classified as one of these types for tax purposes).

    enum: 16 values
  • entityTypeOtherSpecify string optional

    Required only when entityType is other_nonprofit_organization or other.

    length: 0–160
  • entityTypeCorporationFormNumber string optional

    Required only when entityType is corporation, e.g. 1120 or 1120-S.

    length: 0–20
  • entityTypeTrustGrantorTin string optional

    Personal identifier; handle as sensitive data. Required only when entityType is trust.

    pattern
  • entityTypeEstateDecedentSSN string optional

    Personal identifier; handle as sensitive data. Required only when entityType is estate.

    pattern
  • entityTypePlanAdministratorTin string optional

    Personal identifier; handle as sensitive data. Required only when entityType is plan_administrator.

    pattern
  • groupExemptionNumber string optional

    Applies only to certain nonprofit/church-affiliated group-ruling entities.

    length: 0–10
  • incorporationState string optional

    Two-letter USPS state abbreviation. Required only when entityType is corporation and the corporation was incorporated in the U.S.; use incorporationForeignCountry instead for a foreign incorporation.

    pattern
  • incorporationForeignCountry string optional

    Required only when entityType is corporation and the corporation was incorporated outside the U.S.

    length: 0–100

Reason for applying

  • reasonForApplying enum required

    Check only one box.

    enum: 9 values
  • reasonForApplyingSpecify string optional

    Required when reasonForApplying is started_new_business (type of business), changed_type_of_organization (new type), created_a_trust (type of trust), created_a_pension_plan (type of plan), banking_purpose (purpose), or other.

    length: 0–200

Business start date, accounting year, and employees

  • businessStartDate date optional

    YYYY-MM-DD. Not required on every reason-for-applying path (e.g. not needed for a banking-purpose-only application); see the Form SS-4 instructions for line 11.

  • accountingYearClosingMonth enum optional

    The last month of the entity's accounting year (December for a calendar-year filer). Not required on every reason-for-applying path.

    enum: 12 values
  • highestExpectedEmployees integer optional

    If 0, expectedAgriculturalEmployees, expectedHouseholdEmployees, and expectedOtherEmployees, along with line 14/15, may be left unanswered.

    range: 0–∞
  • expectedAgriculturalEmployees integer optional

    Only completed when highestExpectedEmployees is greater than 0.

    range: 0–∞
  • expectedHouseholdEmployees integer optional

    Only completed when highestExpectedEmployees is greater than 0.

    range: 0–∞
  • expectedOtherEmployees integer optional

    Only completed when highestExpectedEmployees is greater than 0.

    range: 0–∞
  • file944AnnuallyElection boolean optional

    Available only if expected employment tax liability is $1,000 or less in a full calendar year (generally, $5,000 or less in total wages, or $6,536 or less in a U.S. territory). If not checked, the entity must file Form 941 quarterly.

  • firstWagesPaidDate date optional

    YYYY-MM-DD. If the applicant is a withholding agent, this is instead the date income will first be paid to a nonresident alien. Only applicable when employees are expected (highestExpectedEmployees greater than 0) or the entity is a withholding agent.

Principal business activity

  • principalActivity enum optional

    Check one box that best describes the principal activity. Not required on every reason-for-applying path.

    enum: 12 values
  • principalActivityOtherSpecify string optional

    Required only when principalActivity is other.

    length: 0–160
  • principalLineOfBusiness string optional

    Free text, e.g. "Residential electrical contracting".

    length: 0–200

Previous EIN

  • previouslyAppliedForEIN boolean required

    A new EIN is generally not issued to the same legal entity twice; see the instructions if unsure whether the entity already has one.

  • previousEIN string optional

    Required only when previouslyAppliedForEIN is true. Format NN-NNNNNNN.

    pattern

Third party designee (optional)

  • thirdPartyDesigneeName string optional

    Personal identifier; handle as sensitive data. Complete this section only to authorize a named individual to receive the entity's EIN and answer questions about this application; the designee's authority terminates once the EIN is assigned and released.

    length: 0–160
  • thirdPartyDesigneePhone string optional

    Required only when thirdPartyDesigneeName is given. In international E.164 format, e.g. +12025551234.

    pattern
  • thirdPartyDesigneeAddressAndZip string optional

    Required only when thirdPartyDesigneeName is given.

    length: 0–200
  • thirdPartyDesigneeFax string optional

    In international E.164 format, e.g. +12025551234.

    pattern

Signature

  • applicantNameAndTitle string required

    Personal identifier; handle as sensitive data. The person signing the application under penalties of perjury, and their title (e.g. "Sole Proprietor", "Managing Member", "Trustee").

    length: 1–160
  • applicantPhone string required

    Personal identifier; handle as sensitive data. In international E.164 format, e.g. +12025551234. The IRS online EIN assistant may use this number to contact the applicant about the application.

    pattern
  • applicantFax string optional

    In international E.164 format, e.g. +12025551234.

    pattern

Verification record

This file is the source-review record for this document version, per the manual-source-review-v1 practice. It documents the provenance of the published fields and flow, records a mock-data test run of the field set, and states the current verification claim honestly.

Current claim

  • status: draft
  • verification.method: manual-source-review-v1
  • verification.lastVerifiedAt: 2026-07-01

The document was derived from and cross-checked against the official sources below, but the full field-by-field comparison the practice requires (confirming every published field, type, requiredness, and constraint against the live form — manual-source-review-v1 → Procedure step 2) has not yet been independently re-verified by a second reviewer. It therefore remains draft, not verified. Consumers SHOULD treat this as an accurate, source-grounded structural reference, not a load-bearing description of the live process.

Sources examined

Not a time-versioned (edition) form

Form SS-4 is revised periodically (the current revision is December 2025, prior revisions include January 2025 and December 2023) but does not carry a fresh required edition each tax/award year the way Form 1040, Form 4868, or FAFSA do — applying the GSP-0005 §2 coexistence test: an EIN application isn't filed "for" a particular year, its fields don't vary by year, and there is no scenario where two editions of the SS-4 data model need to coexist for the same applicant. This document is therefore authored at the plain (non-edition) registry path, registry/us/irs/employer-identification-number-ss4/1.0.0/, the same call made for vehicle-tax and marriage-allowance (see schema-authoring-batches project notes). A future SS-4 revision that changes the field set ships as a new version, not an edition.

What was confirmed against the source

  • Form identity and purpose. Form SS-4 is the application for an EIN, the 9-digit federal tax identifier, filed by employers, sole proprietors, corporations, partnerships, trusts, estates, and other entities. Confirmed against the "About Form SS-4" page and the form's own title block.
  • Full line-by-line field set (lines 1–18). Transcribed directly from the decoded PDF text, including every checkbox-group's option list: entityType (line 9a, 16 options including sole_proprietor, partnership, corporation, trust, remic, etc.), reasonForApplying (line 10, 9 options), and principalActivity (line 16, 12 options). The "specify" sub-fields attached to several checkbox options (entityTypeOtherSpecify, entityTypeCorporationFormNumber, reasonForApplyingSpecify, principalActivityOtherSpecify) and the conditional LLC (8b/8c) and incorporation-state (9b) fields were likewise transcribed from the source text, not inferred.
  • Third Party Designee and signature blocks. Transcribed from the form's final page; the designee-authority-terminates-at-EIN-issuance note and the responsible-party-must-be-an-individual rule (confirmed via the instructions' "How To Apply" section) are recorded in the relevant field descriptions.
  • Online-channel eligibility gate. The IRS EIN online assistant requires the principal business to be in the U.S. or a U.S. territory and the responsible party to hold an SSN or ITIN (not an EIN); confirmed against the online-EIN eligibility page and stated in the document description and the responsiblePartyTaxId field description. This document models the Form SS-4 field set common to every channel (online, fax, mail, and — international applicants only — telephone), not the online assistant's screen-by-screen interview specifically.
  • Alternative channels for out-of-scope applicants. Fax (4-business-day turnaround), mail (~4-week turnaround), and telephone (international applicants without U.S. legal residence/principal place of business only) are documented in the instructions' "How To Apply" section; these are process facts recorded here, not modelled as schema fields (the schema is channel-agnostic).
  • Responsible-party requirement. Per the instructions, the responsible party must be an individual (a natural person), not an entity, except where the applicant itself is a government entity — recorded in responsiblePartyName's description. This requirement applies regardless of the reason for applying, which is why responsiblePartyName/responsiblePartyTaxId are marked required even though several other line items vary by the reason-for-applying branch (see the "Do I Need an EIN?" table on page 2 of the form, which lists a different subset of lines to complete depending on the applicant's situation).

Mock-data test run

Per the issue's phase-4 instruction to test-run the schema with valid mock data, a representative filled-out application was authored and checked field-by-field against every type/required/validation constraint in schema.json (string length, regex pattern, enum membership, numeric minimums, and the conditional-field notes called out in field descriptions):

``json { "entityLegalName": "Riverside Coastal Goods LLC", "tradeName": "Riverside Goods", "mailingAddressLine1": "482 Harbor View Drive, Suite 210", "mailingAddressCity": "San Diego", "mailingAddressState": "CA", "mailingAddressPostalCode": "92101", "principalBusinessCountyAndState": "San Diego County, CA", "responsiblePartyName": "Maria Alejandra Torres", "responsiblePartyTaxId": "512334789", "isLLC": true, "llcMemberCount": 1, "llcOrganizedInUS": true, "entityType": "sole_proprietor", "reasonForApplying": "started_new_business", "reasonForApplyingSpecify": "Online retail of handmade coastal home goods", "businessStartDate": "2026-08-01", "accountingYearClosingMonth": "december", "highestExpectedEmployees": 0, "previouslyAppliedForEIN": false, "applicantNameAndTitle": "Maria Alejandra Torres, Managing Member", "applicantPhone": "+16195550142" } ``

This models a single-member LLC (taxed as a sole proprietorship, the most common individual-formed-entity case, consistent with us/ca/sos/business-entity-llc-formation's scope) applying online for a brand-new business with no employees yet. The scenario exercises the isLLC → llcMemberCount/llcOrganizedInUS conditional pair and the reasonForApplying: started_new_business → reasonForApplyingSpecify pair. A one-off Node script (node:fs + a hand-rolled per-field validator, not committed to the repo) confirmed every populated field satisfies its type and validation constraint and that no required field was left unset:

`` PASS — mock single-member-LLC 'started new business' EIN application satisfies the schema's field-level constraints. ``

Both registry validators were run against the schema document itself (not the mock data) and pass:

``` $ node tools/validate.mjs registry/us/irs/employer-identification-number-ss4/1.0.0/schema.json ok registry/us/irs/employer-identification-number-ss4/1.0.0/schema.json

$ cd tools && node validate-ajv.mjs ../registry/us/irs/employer-identification-number-ss4/1.0.0/schema.json ok registry/us/irs/employer-identification-number-ss4/1.0.0/schema.json [v0.1] ```

Corrections from independent review

The GOV-284 review gate's independent re-derivation of the field set from the live Form SS-4 PDF (per manual-source-review-v1 Procedure step 2) found one content discrepancy, corrected here:

  • isLLC (line 8a) requiredness. The initial authoring marked isLLC as required: true, describing it as required on "essentially every path." The Form SS-4 "Do I Need an EIN?" routing table (page 2) contradicts this: it excludes line 8a from the required-lines list for 3 of the 9 applicant situations — plan administrator, estate administrator, and state/local tax-reporting agency. isLLC is now required: false with a conditional note in its description, matching the pattern already used for the dependent llcMemberCount/llcOrganizedInUS (lines 8b/8c) fields. Every other checked item — the 16/9/12-option enums (entityType/reasonForApplying/ principalActivity), the Form 944 election thresholds, and the line-1–18 + Third Party Designee + signature-block field mapping — matched the decoded PDF text and required no change.

What is NOT yet independently verified

  • The full "Do I Need an EIN?" line-subset table (form page 2) documents nine different applicant situations, each requiring a different subset of lines 1–18. v0.1 has no conditional-flow construct (GSP-0004, not yet accepted), so this document models every line as a single flat field set with required: true only on the items common to essentially every path (entityLegalName, mailingAddressLine1/City, responsiblePartyName, responsiblePartyTaxId, entityType, reasonForApplying, previouslyAppliedForEIN, applicantNameAndTitle, applicantPhone) and required: false with a conditional note on the rest. This is a reasonable flattening, not a verified line-subset mapping for all nine situations. isLLC (line 8a) is a case in point and was corrected during independent source review (see "Corrections from independent review" below): the table excludes line 8a for three of the nine paths (plan administrator, estate administrator, state/local tax-reporting agency), so it is required: false with a conditional note, not required: true.
  • Constraint patterns (SSN/EIN format, ZIP code, E.164 phone) are reasonable encodings, not citations of a published IRS validation rule.
  • The online EIN assistant's actual screen-by-screen interview (question order, exact wording, branching logic) was not directly observed. Unlike the GB DVLA photocard-renewal schema's pre-login screen crawl, IRS.gov's EIN assistant requires an active session to reach past the eligibility gate, so this document is sourced from the paper Form SS-4 and its instructions, which the IRS states the online interview mirrors.
  • State-specific downstream requirements (e.g. a state also requiring its own tax registration after the federal EIN is issued) are out of scope; this document covers the federal EIN application only.

Path to a verified claim (next step)

To advance this document to status: verified, a reviewer applies manual-source-review-v1 (Procedure step 2 field-by-field comparison, step 3 flow comparison) against the live Form SS-4 (Rev. 12-2025) PDF and, ideally, an observed run of the online EIN assistant's interview screens, confirms the sources are still authoritative, resolves any discrepancy by shipping a new schema version (immutability — VERSIONING §3, practice Procedure step 5), and records the outcome here plus sets status: verified with a current verification.lastVerifiedAt / nextReviewBy. This v1.0.0 record stays as the authoring provenance.

Re-verification

Per the practice's Cadence, nextReviewBy is set to 2027-01-01 (6 months). Re-check the source on or before that date, on any source.url change, or when the IRS publishes a new Form SS-4 revision.

View the raw record (VERIFICATION.md)

Version history

Independent and non-affiliated

GovSchema is an independent, open-source project. This reference is not produced, reviewed, or endorsed by Internal Revenue Service or any government. The authoritative source is always the live government form and its official instructions.