At a Glance
The IRS provides an Assurance Testing System (AATS) — a sandbox environment where you can validate your IRIS XML submissions before filing in production. You need an approved IRIS TCC to access it. AATS tests schema compliance, authentication, and transmission workflows without creating real IRS filings. If you use BoomTax, testing is handled internally — you don’t need to interact with AATS directly.
This article is part of our IRS IRIS Resource Center — your complete guide to the FIRE→IRIS migration.

What Is the IRIS Testing Sandbox?

The IRS IRIS testing environment is formally called the Assurance Testing System (AATS). It is a non-production environment that mirrors the live IRIS infrastructure, allowing transmitters to validate their XML submissions, test their authentication workflows, and confirm end-to-end transmission before filing real information returns.

AATS is not optional for new IRIS transmitters. The IRS requires that software developers and transmitters applying for an IRIS TCC pass AATS testing as part of the approval process. You must demonstrate that your system can generate valid XML, authenticate correctly, transmit files, and retrieve acknowledgments before the IRS will activate your TCC for production use.

This is a significant departure from FIRE, where the testing process was simpler — upload a test file to the FIRE test system, receive a pass/fail response, and move on. IRIS AATS testing is more rigorous because the A2A API is more complex and the XML format has stricter validation requirements.

How to Access the IRIS Sandbox

Prerequisites

Before you can access AATS, you need:

  1. An IRS e-Services account with completed ID.me identity verification. See our IRIS registration guide for step-by-step instructions.
  2. An IRIS TCC application in progress (or approved). The IRS grants AATS access as part of the TCC application workflow. You do not need a fully approved TCC to begin testing — the IRS typically opens sandbox access during the suitability review period.
  3. The IRIS A2A technical documentation. The IRS publishes WSDL files, XSD schemas, and endpoint URLs for the AATS environment separately from production. These are available through your e-Services account once AATS access is granted.

Sandbox Endpoints

The AATS environment has its own set of SOAP endpoints, distinct from production. Do not confuse them — submitting to AATS endpoints does not create real IRS filings, and submitting to production endpoints during testing will create real filings that you would need to correct. The IRS provides the AATS endpoint URLs through the e-Services portal. They typically follow a different subdomain pattern than production endpoints.

Authentication in AATS works the same way as production: you authenticate with your TCC credentials, receive a session token, and include that token in subsequent API calls. This is by design — the IRS wants to verify that your authentication implementation works correctly before granting production access.

What You Can Test

XML Schema Validation

AATS validates your XML submissions against the same XSD schemas used in production. This catches structural errors — missing elements, incorrect data types, namespace mismatches, and element ordering issues — before you submit to the live system. If you are converting FIRE flat files to IRIS XML, schema validation in AATS is essential for verifying that your conversion logic produces conformant output.

Schema Compliance Across Form Types

Each 1099 form type has its own schema requirements. AATS allows you to test submissions for every form type your TCC covers. If you file 1099-NEC, 1099-MISC, 1099-INT, and 1099-DIV, test all four — do not assume that passing validation for one form type means the others will also pass. Field requirements, amount relationships, and optional elements differ across form types.

Transmission Workflow

AATS tests the complete transmission lifecycle:

  1. Authentication: Verify your credentials are accepted and tokens are returned correctly.
  2. Submission: Upload your XML and confirm the SOAP response indicates successful receipt.
  3. Status check: Poll the status endpoint to confirm your submission is processing.
  4. Acknowledgment retrieval: Download the acknowledgment response, which confirms acceptance or lists any validation errors.

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Testing Limitations

While AATS mirrors the production environment closely, there are important differences to be aware of:

  • No TIN validation against IRS records: AATS does not check TINs against the IRS Master File. A submission with a fake or invalid TIN will pass AATS testing but may fail or trigger a notice in production. Use the IRS TIN Matching program separately to validate TINs.
  • Processing time differences: AATS may process submissions faster or slower than production, depending on system load. Do not benchmark production performance expectations based on AATS response times.
  • Rate limits may differ: The AATS environment may have different rate limits than production. Do not assume that because your system can submit 100 files per minute in AATS, it will be able to do the same in production.
  • Data does not persist long-term: Test submissions in AATS are periodically purged. Do not rely on AATS for record retention.
  • Limited form type coverage during rollout: As the IRS expands IRIS to cover new form types (beyond 1099s), the AATS schemas for new form types may lag slightly behind production availability. Check the IRS IRIS release notes for schema availability updates.

Best Practices for IRIS Testing

Test with Realistic Data Volumes

If you plan to file 10,000 returns in production, do not test with a single return and call it done. Test at a volume that represents your actual filing load. This exposes performance bottlenecks, timeout issues, and rate limit problems that single-record tests miss. Organizations planning high-volume bulk filing should simulate their full production volume in AATS.

Test Corrections and Amendments

Filing original returns is only half the workflow. You also need to test corrections — filing amended returns to fix errors in previously accepted submissions. The correction process in IRIS differs from FIRE’s correction workflow, and AATS is the place to learn it before you have a real correction deadline bearing down on you.

Test Edge Cases

Push the boundaries of your data:

  • Submissions with the maximum number of payee records
  • Forms with every optional field populated
  • Forms with only required fields (minimum data)
  • Foreign addresses and non-standard characters
  • Large dollar amounts near the field maximum
  • Multiple form types in a single transmission batch

Automate Your Test Suite

If you are building a custom IRIS A2A integration, write automated tests that run against AATS. Include tests for successful submissions, expected validation failures, authentication edge cases, and status polling loops. Automated tests catch regressions when you update your code or when the IRS updates its schemas.

BoomTax and IRIS Testing

If you use BoomTax as your filing provider, you do not need to interact with AATS at all. BoomTax maintains its own IRIS integration, manages all testing internally, and ensures that every submission complies with the current IRS schemas before it reaches production. When the IRS publishes schema updates, BoomTax updates its systems and re-tests — you are insulated from the process entirely.

This is particularly valuable for organizations transitioning from FIRE. Rather than learning the IRIS A2A protocol, building a testing pipeline, passing AATS certification, and maintaining it going forward, you can upload your existing FIRE-format files to BoomTax and let BoomTax handle everything downstream.

Frequently Asked Questions

Yes. AATS access is tied to the IRIS TCC application process. You need at minimum an in-progress IRIS TCC application to access the sandbox. The IRS typically grants AATS access during the suitability review period, before your TCC is fully approved for production. If you use a provider like BoomTax, you skip both the TCC and testing requirements entirely.

The time depends on your technical readiness. If your XML generation and SOAP integration are already solid, you can complete AATS testing in a few days. If you are building from scratch, expect 2–4 weeks of development and testing. The IRS reviews your test results as part of the TCC approval process, which itself takes 45+ days. Plan for the entire testing and approval cycle to take 2–3 months.

AATS does not validate TINs against the IRS Master File, so you can use test TINs or real TINs — neither will be checked for validity against IRS records. However, for security reasons, most organizations use synthetic test data rather than real taxpayer information in a non-production environment. The IRS provides guidance on acceptable test TIN formats in its AATS documentation.

This most commonly occurs due to TIN validation (AATS does not check TINs against IRS records, but production does), rate limit differences between environments, or schema version mismatches if the IRS updated production schemas after you tested. Ensure you are using the latest XSD schemas, validate TINs separately using the IRS TIN Matching program, and test at realistic volumes. See our IRIS error codes guide for troubleshooting specific production failures.

Next Steps

Ken Ham
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Ken Ham
Founder at BoomTax
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Passionate about making tax compliance simple so businesses can focus on what matters.

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