If you’re the person responsible for getting 1099s, W-2s, or other information returns to the IRS electronically, you need to understand exactly what’s changing when FIRE shuts down on December 31, 2026. Not the marketing version – the technical version.
This guide breaks down every meaningful technical difference between FIRE and IRIS – from data formats to authentication to error handling. Whether you’re an in-house developer, an IT director evaluating migration options, or a CPA trying to advise clients, this is what you need to know.
The Fundamental Shift: Flat Files to Structured XML
This is the change that affects everyone. FIRE accepts fixed-width flat files defined by IRS Publication 1220. Every field occupies a specific character position – payer TIN starts at position 12 and runs through position 20, payment amount starts at position 55, and so on. One misplaced character and the entire file can fail.
IRIS replaces this with structured XML documents that follow IRS-defined schemas. Instead of counting character positions, you use tagged elements like <PayerTIN> and <PaymentAmount>. The data is self-describing – a parser can read it without knowing the layout in advance.
Data Format: What Changes in Practice
Let’s look at what the same data looks like in both systems. Here’s a simplified 1099-NEC payee record:
FIRE Format (Publication 1220)
In FIRE, a B record (payee) is a single line of exactly 750 characters. Every field is at a fixed position:
Pos 1: B ← Record type Pos 2-5: 2026 ← Tax year Pos 12-20:123456789 ← Payer TIN Pos 21-40:987654321··········· ← Payee TIN (left-padded) Pos 55-66:000005000000 ← Amount ($50,000.00) ...750 total characters per record
IRIS Format (XML Schema)
The same data in IRIS XML is self-documenting:
<Form1099NEC> <PayerTIN>123456789</PayerTIN> <RecipientTIN>987654321</RecipientTIN> <NonemployeeCompensation>50000.00</NonemployeeCompensation> <TaxYear>2026</TaxYear> </Form1099NEC>
The XML is more verbose but far easier to debug. When IRIS rejects a return, it can point to <NonemployeeCompensation> instead of saying “error at position 55-66.” For teams that have spent years decoding cryptic FIRE rejections, this is a meaningful improvement.
Authentication: From Simple Login to Modern Security
FIRE authentication was straightforward – sometimes too straightforward. You logged into the FIRE website with a username and password, entered your TCC, and uploaded files through a browser form. No API, no tokens, no OAuth.
IRIS modernizes this significantly:
- A2A (Application-to-Application) channel: Uses OAuth 2.0 with client credentials. Your system authenticates programmatically, receives an access token, and submits returns via API. This is the path for automated, system-to-system filing.
- ISS-UI (Online Portal): Browser-based manual entry for small-volume filers. Uses IRS login credentials (similar to FIRE’s portal, but modernized).
- TCC remains required: Both channels require a valid IRIS TCC. However, FIRE TCCs don’t transfer to IRIS – you need to apply for a new one.
API Access: The Biggest Technical Win
For developers and IT teams, the IRIS API is the single biggest improvement over FIRE. FIRE had no programmatic interface whatsoever. Every submission required someone to manually log into a website and upload a file.
IRIS offers a full REST API with:
- Submission endpoints: POST returns individually or in batches
- Status endpoints: Poll for acceptance/rejection status programmatically
- Correction endpoints: Submit corrections through the same API
- Testing sandbox: A complete test environment with test TCCs where you can validate your integration before going live
This means you can build a fully automated pipeline: your system generates XML, authenticates, submits, and checks status – all without human intervention. For large filers processing thousands of returns, this eliminates the manual bottleneck that FIRE always was.
Error Handling: From Guessing to Knowing
Anyone who has dealt with FIRE rejections knows the frustration. You upload a file, wait for batch processing, and get back something like “Error Code 301 – Record B, Sequence 0047.” What’s wrong with record 47? FIRE didn’t always make it obvious.
IRIS takes a fundamentally different approach:
With IRIS, a validation failure tells you exactly which field failed, what the invalid value was, and what the schema expects. You can build error handling into your automated pipeline – parse the API response, map errors to records, and even auto-correct common issues before resubmitting. For a complete reference, see our IRIS error codes guide.
TCC: Same Concept, Different System
Both FIRE and IRIS require a Transmitter Control Code (TCC) to submit returns. But they’re separate codes in separate systems:
- FIRE TCCs are tied to the FIRE system and become useless when FIRE shuts down
- IRIS TCCs must be applied for separately through the IRS’s IRIS registration process
- The application process takes up to 45 days
- You need separate TCCs for production and testing
If you’re filing directly through IRIS, apply for your TCC now. If you’re using a provider like BoomTax, you don’t need your own TCC at all – we file under ours.
Testing: Finally, a Real Sandbox
FIRE’s testing capabilities were limited. You could submit test files, but the environment didn’t closely mirror production, and feedback was sparse.
IRIS provides a full sandbox environment that mirrors production:
- Separate test TCC (applied for during registration)
- Full schema validation against the same rules as production
- Realistic error responses so you can build proper error handling
- No risk of accidentally submitting real returns
If you’re building a direct IRIS integration, plan for at least 2-4 weeks of sandbox testing before your first production submission. The sandbox will catch schema issues, authentication problems, and edge cases that are far cheaper to fix before January.
State Filing: What Stays the Same
The Combined Federal/State Filing (CF/SF) program continues to work through IRIS. If you participate in CF/SF today through FIRE, the program carries forward – but the submission format changes to XML along with everything else.
States that require direct filing (outside the CF/SF program) are unaffected by the FIRE shutdown. Those submissions were never through FIRE to begin with.
Migration Paths: Three Options
Based on the technical differences, organizations typically choose one of three approaches:
Option 1: Build Direct IRIS Integration
Best for: Large organizations with dedicated development teams and thousands of returns. Timeline: 3-6 months. Requires: IRIS TCC, XML development, OAuth implementation, sandbox testing, error handling pipeline.
Option 2: Use the IRIS Free Portal
Best for: Small filers with under 50 returns. Timeline: Immediate (after TCC approval). Requires: IRIS TCC, manual data entry. Limitation: No automation, no batch upload, not practical for volume.
Option 3: Use a Filing Provider
Best for: Everyone in between – and organizations that want IRIS compliance without the development project. Timeline: Same day. Requires: Nothing. The provider handles format conversion, TCC, submission, and status tracking.
What BoomTax Handles for You
If you’re evaluating whether to build or buy, here’s what BoomTax abstracts away:
- Format conversion: Upload FIRE flat files, CSV, or use our API – we generate the IRIS XML
- TCC management: No application, no 45-day wait – we file under our TCC
- Schema compliance: We track IRS schema updates so you don’t have to
- Error resolution: IRIS errors are mapped to your records with plain-language explanations
- Status tracking: Real-time filing status in your dashboard, no API polling needed
- State filing: CF/SF and direct state filing handled alongside federal
BoomTax also offers a full REST API if you want programmatic access without building the IRIS layer yourself. Submit returns via our API, and we handle the IRIS submission behind the scenes.
Frequently Asked Questions
Can I submit FIRE-format files to IRIS?
No. IRIS requires XML. FIRE flat files will be rejected. If your systems produce FIRE-format files, you need to either rewrite your export pipeline or use a provider like BoomTax that accepts FIRE files and converts them to IRIS XML.
Does the IRIS XML schema change year to year?
Yes. The IRS updates the IRIS schema for each tax year. If you build a direct integration, you need to track these changes and update your XML generation logic annually. Filing providers handle this automatically.
Is the IRIS API REST or SOAP?
REST. The IRIS A2A channel is a modern REST API using JSON for metadata and XML for return data. OAuth 2.0 client credentials flow for authentication.
What about W-2 filing?
W-2s are filed through the SSA’s Business Services Online (BSO), not FIRE or IRIS. The FIRE shutdown doesn’t directly affect W-2 filing. However, if your combined filing workflow handled both 1099s (via FIRE) and W-2s (via BSO) in the same pipeline, you’ll need to update the 1099 portion.
Can I use both FIRE and IRIS during 2026?
Yes. During 2026, both systems are available. This is the ideal time to test IRIS submissions while FIRE is still your fallback. By January 2027, FIRE is gone.
What happens to returns already submitted through FIRE?
Returns submitted through FIRE before it shuts down are processed normally. You don’t need to resubmit anything. Only new submissions after December 31, 2026 must go through IRIS.
The Bottom Line for Technical Teams
IRIS is a genuine improvement over FIRE – the XML format is cleaner, the API enables automation, the error handling is actionable, and the sandbox is usable. But it’s also a significant technical migration if you’re doing it yourself.
For most organizations, the practical choice is to let a provider handle the IRIS layer while you focus on what you do best. BoomTax gives you the same data input flexibility you’ve always had – including FIRE-format flat file uploads – with full IRIS compliance on the back end.
Create your free BoomTax account and test a submission today – whether you’re evaluating providers or just want to see what IRIS filing looks like without building the integration yourself.
BoomTax, The Boom Post, and its affiliates do not provide tax, legal or accounting advice. This material has been prepared for informational purposes only, and is not intended to provide, and should not be relied on for, tax, legal or accounting advice. You should consult your own tax, legal and accounting advisors prior to engaging in any transaction.
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