Complete IRS Modernized e-File (MeF) Assurance Testing System (ATS) testing before moving e-file software to production
domain: government-tax · 5 steps · contributed by waymark-seed
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Steps
Check the current ATS testing window on the IRS's MeF ATS page before submitting scenarios — for the cycle documented there, 'ATS is scheduled to open Oct. 10, 2025, 9 a.m. Eastern time. Testing will begin Oct. 14, 2025, 9 a.m. Eastern time,' and scenarios submitted for review before that date 'will be treated as though they were received on Oct. 14.'
Identify the ATS scenario form family relevant to your software (the IRS page lists separate scenario sets and known-issues files per form family, e.g., 1040 series and extensions, 1041, 1065, 1120, 94x, 2290, 7004, 8849, 8868, 709, 720, and 990/1120-POL).
Download and review the published 'known issues and solutions' file for your form family before testing — the IRS updates these files repeatedly during a cycle (the page's comment history shows multiple dated updates per form family within a single testing season).
Submit your ATS test scenarios against the relevant form family and monitor IRS MeF ATS call logs published for that testing cycle.
Use the separate 'MeF user guides and publications' page to find all MeF publications, and the 'MeF status' page for information on distribution of new MeF web service definition language (WSDL) files, since these are maintained separately from the ATS scenario page itself.
Known gotchas
ATS known-issues files are revised multiple times within a single testing cycle — the IRS page shows repeated dated updates (e.g., several updates to the 1040 series and extensions known-issues file across October–December for one cycle), so re-check for updates immediately before finalizing test submissions.
ATS scenarios are organized per form family, not as one universal test set — confirm you are testing against the correct form-family scenario package for the tax year and form you intend to e-file.
The IRS states 'the tests do not contain every possible condition; therefore, once a Software Developer has passed ATS testing, they may self-test additional conditions appropriate to its product and clientele' — passing ATS is not itself a guarantee that every condition your software encounters in production has been exercised.
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