The IRS FIRE system will be permanently decommissioned on December 31, 2026. All 2026 information returns, filed in early 2027, must be submitted through IRIS. For mid-market and enterprise filers, that means new file formats, new credentials, new validation logic, and a filing architecture that requires planning well before filing season opens.
If your organization files 10 or more information returns electronically, this transition affects you directly. FIRE has been the backbone of IRS electronic filing since the 1980s. What replaces it is structurally different, and the gap between your current workflow and IRIS compliance is likely larger than it appears.
This guide breaks down exactly what’s changing, what mid-market and enterprise filers need to do, and where the transition gets operationally complex.
What Is IRIS, and How Does It Differ from FIRE?
IRIS, the Information Returns Intake System, is the IRS’s modern replacement for the FIRE system. The two platforms are not interchangeable, and you cannot simply redirect your existing FIRE workflow to IRIS.
Here’s how the core differences break down:
| Aspect | FIRE (Legacy) | IRIS (New) |
| Status | Retires December 31, 2026 | Required for Tax Year 2026 filings |
| File Format | 1220 flat file | XML (A2A) or CSV (portal) |
| File Size Limit | 100MB compressed | 250MB uncompressed |
| Validation | Post-submission | Real-time, pre-acceptance |
| Error Correction | Full file replacement | Targeted record-level corrections |
| Intake Options | Single upload interface | Taxpayer Portal or A2A API |
| TCC | FIRE-specific TCC | New IRIS-specific TCC required |
Under FIRE, you submitted a file and found out, sometimes 24 to 48 hours later, whether it was accepted. Under IRIS, validation happens before acceptance. That’s a meaningful improvement for data accuracy, but it shifts the burden upstream: your data needs to be clean before you submit, not corrected after the fact.
The Two IRIS Filing Paths: Which One Applies to You?
IRIS offers two intake channels. Which one you use depends on your filing volume.
1. IRIS Taxpayer Portal
The portal supports manual data entry and CSV uploads for smaller filings. It’s designed for filers submitting fewer than 100 returns at a time. For organizations managing hundreds or thousands of forms across multiple entities, the portal’s 250-return CSV cap creates a bottleneck that makes it impractical at scale.
2. IRIS Application-to-Application (A2A)
For high-volume filers, A2A is the required path when submitting 100 or more returns. It transmits returns in XML format via secure API, supports up to 100MB per transmission, and connects your internal systems directly to IRIS. This is where the real technical lift begins.
To file via A2A, your organization must:
- Apply for an IRIS A2A-specific TCC, separate from your existing FIRE TCC, with a processing time of up to 45 days
- Obtain an API Client ID, required for IRS system access
- Download the current IRS XML schema package, and map your data fields to it
- Complete IRIS Assurance Testing System (ATS) testing, mandatory before live submissions are accepted
None of these steps can be completed at the last minute. Each one depends on the previous, and the IRS ATS window requires advance coordination.
What Has to Change in Your Internal Systems?
The FIRE-to-IRIS shift touches more than your submission process. Here are the operational areas most likely to require attention.
File Format and Data Structure
FIRE used the Publication 1220 flat-file format, where every record followed a fixed character-position layout. IRIS uses structured XML, where data lives in clearly labeled fields. That sounds like an upgrade, and it is, but converting legacy output from your ERP, AP, or payroll systems into IRS-compliant XML requires new logic, new mapping, and testing.
According to Sovos, 26% of organizations still generate 1220 text files for upload, and 19% either upload manually or rely on another provider. If your organization falls into either category, you’ll need to redesign your filing process from the ground up.
Name Field Separation
FIRE accepted a single combined name field. IRIS requires separate fields for first name, middle name, and last name. Without logic in place to split names accurately, you risk Name/TIN mismatches, which trigger B-Notices and IRS penalties.
Multi-Entity Filings
When you file for multiple business entities, IRIS requires a transmitter setup rather than separate issuer accounts. Switching between issuer accounts is operationally inefficient and increases the risk of filing errors at scale. Mid-market and enterprise organizations managing subsidiaries, trusts, or affiliated entities need to account for this in their architecture decisions.
State-Level Filing
This is where dual-format complexity enters the picture. The IRS has moved to IRIS, but most states still rely on the FIRE format. As of early 2025, only a small number of states had adopted the IRIS schema. That means your team may need to maintain both XML for federal filings and 1220 flat-file output for state submissions, until individual states update their own systems.
Where Mid-Market and Enterprise Teams Face the Most Risk
The technical requirements of IRIS A2A are well-documented. The operational risks are less obvious. Here’s where complex filing environments tend to break down.
Recurring corrections at volume. IRIS flags errors before acceptance, which reduces post-submission rejections. But when errors do occur, especially across hundreds of records, each one requires a manual fix and re-upload. At high volume, that process slows your filing operation significantly.
Mixed data sources. IRIS expects clean, standardized data conforming to its XML schema. If your 1099 data lives across multiple source systems, AP platforms, payroll providers, treasury tools, standardizing it for IRIS submission requires upstream data governance work that goes beyond what your filing software can handle alone.
Complex form types. Forms like 1042-S and 1099-DA are supported by IRIS but carry additional reporting fields, validation rules, and schema-level complexity compared to a standard 1099-NEC workflow. If your filing mix includes these forms, plan for extended testing time.
Ongoing A2A maintenance. A2A filing isn’t a one-time setup. Every IRS XML schema update requires your integration to be re-evaluated and adjusted. That requires dedicated IT and compliance resources, not just during onboarding, but continuously.
Your IRIS Transition Checklist
Use this checklist to assess where your organization stands and what still needs to happen before the 2027 filing season.
- Confirm which forms you file and verify IRIS supports them
- Determine your filing volume to establish whether A2A is required
- Apply for a new IRIS-specific TCC (allow up to 45 days)
- Apply for an API Client ID if using A2A
- Download the current IRS IRIS XML schema package
- Map your source data fields to IRIS XML requirements
- Test name-splitting logic to prevent TIN mismatch errors
- Complete IRIS ATS testing before live submission
- Assess state filing requirements for dual-format compliance
- Review your multi-entity structure for transmitter setup needs
- Confirm your compliance platform has fully migrated to IRIS
A polling survey from a Sovos IRIS transition webinar found that 31% of attendees identified understanding and incorporating IRIS’s technical requirements as their biggest challenge, and 25% were uncertain whether their source systems could support IRIS at all. If either of those concerns applies to your team, the time to address them is now, not in Q4 2026.
Start Your Transition Before the Deadline Closes In
The FIRE system retires on December 31, 2026. That’s one remaining filing season to complete your transition. For organizations managing high-volume, multi-entity, or complex-form filings, that window is tighter than it looks.
The organizations best positioned for the 2027 filing season are the ones that have already completed TCC applications, XML mapping, and ATS testing, and are using a compliance platform that has already migrated to IRIS.
1099Pro Cloud is fully IRIS-ready, with built-in IRIS-ready compliance, TIN matching, and multi-entity management. Your team can file with confidence, without rebuilding your workflow from scratch.
Frequently Asked Questions
What is the IRIS transition deadline for enterprise filers?
The IRS FIRE system will be permanently decommissioned on December 31, 2026. All 2026 tax year information returns, filed in early 2027, must be submitted through IRIS. There are no exceptions for high-volume or enterprise filers.
Can I reuse my existing FIRE TCC for IRIS?
No. Your existing FIRE Transmitter Control Code (TCC) cannot be used with IRIS. You must apply for a new IRIS-specific TCC through the IRS e-Services portal. The application process can take up to 45 days, so early submission is strongly recommended.
When is IRIS A2A required versus the Taxpayer Portal?
IRIS A2A is required when submitting 100 or more information returns. The Taxpayer Portal supports manual entry and CSV uploads for smaller filing volumes, with a limit of 250 returns per CSV upload. For mid-market and enterprise filers, A2A is typically the appropriate path.
How does IRIS affect state-level filing compliance?
Most states have not yet adopted the IRIS XML schema and still process information returns using the FIRE flat-file format. Until individual states update their systems, you may need to maintain both XML output for federal IRIS submissions and 1220 flat-file output for state filings. Check the requirements for each state where you file.
What data changes do I need to make before filing through IRIS?
The most common required changes include: converting 1220 flat-file output to IRS-compliant XML, separating combined name fields into distinct first/middle/last fields, standardizing data from multiple source systems, and completing field-level mapping to the current IRIS XML schema. For A2A filers, all changes must be validated through IRS ATS testing before live submissions are accepted.
How long does IRIS ATS testing take for A2A filers?
Testing timelines vary depending on your organization’s technical readiness and IRS scheduling. Given that you must first obtain a TCC (up to 45 days) and an API Client ID before ATS testing can begin, the full onboarding process for A2A filers typically spans several months. Organizations that have not yet started should begin immediately.