name: IRS API Rate Limits
description: >-
  The IRS does not publicly publish specific numeric rate limits (requests per
  second/minute) for its APIs. Known volume limits and operational constraints
  are documented below based on publicly available IRS guidance. The IRS MeF
  system includes a resiliency feature that allows the application to function
  in a limited capacity during system outages. All APIs require TLS 1.2 or
  higher for connections.
url: https://www.irs.gov/tax-professionals/get-an-api-client-id
rateLimits:
  - api: TIN Matching (Interactive)
    name: Interactive TIN Matching Session Limit
    description: >-
      Interactive TIN Matching allows verification of up to 25 TIN/name
      combinations per session with immediate results.
    limit: 25
    unit: combinations per session
    type: SessionLimit
    url: https://www.irs.gov/tax-professionals/taxpayer-identification-number-tin-matching
  - api: TIN Matching (Bulk)
    name: Bulk TIN Matching Submission Limit
    description: >-
      Bulk TIN Matching allows submission of up to 100,000 TIN/name
      combinations per request. Results are returned within 24 hours.
    limit: 100000
    unit: combinations per submission
    type: BatchLimit
    url: https://www.irs.gov/tax-professionals/taxpayer-identification-number-tin-matching
  - api: MeF
    name: MeF System Availability Window
    description: >-
      The Modernized e-File (MeF) system has defined annual availability windows.
      Business tax return filing opens at 9 a.m. Eastern on approximately
      January 13 each year. Individual tax return filing opens at 9 a.m. Eastern
      on approximately January 26 each year. The system may operate in limited
      capacity during outages.
    type: AvailabilityWindow
    url: https://www.irs.gov/e-file-providers/modernized-e-file-mef-status
  - api: IVES
    name: IVES Transcript Delivery SLA
    description: >-
      A2A transcript requests submitted through IVES are delivered within
      hours. Fax-based requests have a 2-3 business day processing time.
      No published numeric rate limit per API client, but bulk usage
      requires IVES participant enrollment.
    type: SLA
    sla: hours (A2A)
    url: https://www.irs.gov/individuals/income-verification-express-service-for-participants
notes:
  - The IRS does not publish explicit requests-per-second or requests-per-minute limits in public documentation.
  - For specific rate limit guidance, contact the IRS e-Help Desk at 866-255-0654.
  - All connections must use TLS 1.2 or higher with SHA-256 or higher cryptographic signatures.
  - Authentication uses Client ID and signed JWT Bearer tokens (OAuth-style) to obtain access tokens.