IRS Publication 5165 – IRS Forms, Instructions, Pubs 2026

IRS Publication 5165 – IRS Forms, Instructions, Pubs 2026 – The Affordable Care Act (ACA) requires insurers, self-insured employers, and applicable large employers (ALEs) to report health coverage details to the IRS and individuals. IRS Publication 5165 serves as the primary technical guide for software developers and transmitters handling these filings electronically through the ACA Information Returns (AIR) system.

This comprehensive resource details communication procedures, XML transmission formats, business rules, validation processes, and error handling for Forms 1094-B, 1095-B, 1094-C, and 1095-C. The latest version, Publication 5165 (Rev. 12-2025) (updated July 2025), applies to Processing Year 2026 and supports filings for recent tax years.

Whether you develop ACA filing software, transmit returns on behalf of clients, or handle your own organization’s reporting, this guide explains how to comply efficiently and avoid rejections or penalties.

Download the official IRS Publication 5165 PDF here: https://www.irs.gov/pub/irs-pdf/p5165.pdf

Who Needs IRS Publication 5165?

Publication 5165 targets three main groups:

  • Software Developers — Building or updating software to generate compliant XML files and transmit via the AIR system.
  • Transmitters — Third-party providers submitting returns electronically for issuers or employers.
  • Issuers — Employers, insurance companies, or self-insured entities filing their own ACA information returns (or using software/transmitters).

The publication pairs with related IRS resources like Publication 5164 (AATS testing), Publication 5258 (submission composition), Publication 5308 (automated enrollment), and Publication 4557 (safeguarding taxpayer data).

Electronic Filing Requirements for ACA Information Returns

The IRS mandates electronic filing for most ACA reporters. You must file electronically if submitting 10 or more information returns of the same type (e.g., 1095-C) in a calendar year. This threshold, lowered from 250 by final regulations in 2023, applies separately to original and corrected returns and aggregates across certain information return types.

Covered Forms (but not Form 1095-A):

  • Form 1094-B and 1095-B — For health insurance issuers and self-insured plans.
  • Form 1094-C and 1095-C — For applicable large employers reporting offers of coverage to full-time employees.

Transmittal forms (1094-B/C) accompany detailed individual forms (1095-B/C). In some cases, you can submit a standalone 1094-C.

Pro Tip: Even filers below the 10-return threshold are encouraged to file electronically for faster processing and fewer errors.

Examples of Form 1095-C, a key ACA information return covered in Publication 5165.

How to Get Started: Obtaining a Transmitter Control Code (TCC)?

All electronic filers need a unique Transmitter Control Code (TCC) specific to ACA reporting (distinct from FIRE or other TCCs).

Steps to apply:

  1. Create or access an e-Services account via ID.me.
  2. Submit the ACA Application for TCC through e-Services (Responsible Officials and contacts must have accounts).
  3. Designate roles: Software Developer (for testing), Transmitter, and/or Issuer.
  4. Await approval and receive your TCC.

Use separate TCCs for testing (AATS) and production environments. Publication 5165 includes tables for permissible Responsible Official titles and role selection guidance.

Related resource: IRS ACA TCC application page and Publication 5945 tutorial.

Transmission Channels: UI vs. A2A

Publication 5165 details two secure channels for submitting files to the AIR system:

  • Information Submission Services User Interface (ISS-UI) — Browser-based portal. Ideal for smaller volumes or manual uploads. Log in with ID.me, upload Manifest and Form Data XML files.
  • Application-to-Application (A2A) — Automated SOAP-based web services for high-volume transmitters. Requires X.509 digital certificates from authorized Certificate Authorities (e.g., ORC ECA or IGC), WS-Security headers, and Automated Enrollment (see Publication 5308).

Common requirements for both channels:

  • Files must use UTF-8 encoding (no BOM).
  • Form Data File size limit: 100 MB uncompressed (split larger submissions).
  • Unique Transmission Identifier (UTID) in a specific format.
  • Manifest file with checksum (SHA-256), TCC, and other metadata.
  • No mixing of form types or tax years in one submission.

Security standards include TLS 1.2/1.3, threat mitigation (e.g., blocking code/SQL injection), and proper certificate key usage.

Example flowchart illustrating steps in preparing and transmitting ACA returns via the AIR system.

Technical Specifications and XML Schemas

Publication 5165 provides precise formatting rules:

  • Use IRS-published XML schemas (available on the AIR page) for each tax year.
  • Schema versioning: Minor updates allow backward compatibility; major changes require the new version.
  • Prohibited characters: Double dash (–) and hash (#) are not allowed.
  • Escape special characters: & → &amp;, < → &lt;, etc.
  • No empty or null tags (required since 2017).
  • Repeating groups (e.g., covered individuals) have defined limits.

Transmitters must validate files against schemas and business rules before submission. The IRS publishes schemas, business rules, and release memos on the official ACA Information Returns page.

Do not mix tax years within a submission or transmission. Use the current-year Manifest schema even for prior-year data.

Testing and Certification: ACA Assurance Testing System (AATS)

Before live production filing, software developers and transmitters must complete testing:

  • AATS — Test environment for schema validation, business rules, and communication testing.
  • Submit test files using a Test-status TCC.
  • Achieve “Accepted” status on test transmissions.
  • Contact the AIR Help Desk to move to Production status (allow 48 hours).

Publication 5164 complements this with specific test scenarios and packages. Thorough testing prevents costly production rejections.

Acknowledgements, Errors, and Corrections

After submission, the AIR system returns a Receipt ID. Wait about 10 minutes, then retrieve acknowledgements:

  • Status codes: Accepted, Rejected, Partially Accepted, Accepted with Errors, etc.
  • Error Data File — Details schema failures, business rule violations, or TIN issues with XPath references for easy correction.

Correction process:

  • Use Transmission Type “C” (Correction) and reference the original Unique Submission/Record ID.
  • Replacements (“R”) are allowed in limited cases within 60 days.

Common error categories include manifest issues, schema validation failures, and shared business rule violations (prefixed AIRER, AIRSH, AIRBR, etc.).

Publication 5165 includes detailed tables of fault codes (TPE errors) and acknowledgement schemas to help diagnose and resolve issues quickly.

Security and Data Safeguarding Best Practices

Protecting sensitive taxpayer data is mandatory. Follow Publication 4557 guidelines for encryption, access controls, and incident response. Use FIPS-compliant cryptography, manage certificates carefully (revocation checks, expiration), and ensure private keys remain secure.

Key Deadlines and Extensions

  • Due dates typically align with Form 1095 recipient copies (January 31) and IRS transmittals (February/March, depending on type and method).
  • Request extensions via Form 8809 (for filing) or written requests (for recipient copies).

Always verify current-year deadlines on IRS.gov.

Frequently Asked Questions (FAQs)

  • Q: Can I file paper returns if under 10 forms?
    A: Yes, but electronic filing is recommended and often more efficient.
  • Q: Do I need different software for 1094-B vs. 1094-C?
    A: Schemas differ; use the correct one for each form type. Do not mix in one submission.
  • Q: How long should I retain copies of filed returns?
    A: At least three years from the due date.
  • Q: Where do I find the latest schemas?
    A: On the IRS ACA Information Returns (AIR) page under the specific tax year.

Conclusion: Stay Compliant with IRS Publication 5165

IRS Publication 5165 remains the authoritative blueprint for building robust, compliant ACA electronic filing solutions. By following its guidelines on XML formatting, transmission protocols, testing procedures, and error resolution, software developers and transmitters can minimize rejections, protect sensitive data, and meet IRS requirements efficiently.

For the most current information, always download the latest revision from IRS.gov and monitor the AIR page for schema updates or QuickAlerts. Proper implementation not only ensures compliance but also streamlines operations for high-volume filers.

Need help? Consult the AIR Help Desk or work with experienced ACA software providers. Start by reviewing Publication 5165 today and testing in the AATS environment well before deadlines.

This article is for informational purposes and based on official IRS sources as of early 2026. Tax rules can change—verify directly with the IRS for your specific situation.