Table of Contents
Publication 5258 — Guide for Affordable Care Act (ACA) Information Returns (AIR) Submission Composition and Reference Guide · 2026-10-03 edition · updated 2026-10-04 · United States
Section 1 Introduction 2
1.1 | Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 | Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 | Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 | Related Documents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Section 2 Interface Overview 5
2.1 | ISS-UI Channel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 | ISS-A2A Channel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Section 3 Composing IRS ACA Information Returns Transmission 8
3.1 | Namespace and Prefix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 | Guidelines for Composing IRS Form Data File . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 | IRS Form Data File Naming Convention. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4 | Structure of IRS Form Data File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4.1 | Manifest Transmission XML Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4.2 | Uniquely Identifying Transmissions, Submissions, and Records . . . . . . 15
3.4.3 | Computing Checksum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Section 4 Transmitting IRS ACA Form Data File and Retrieving Acknowledgment via the ISS-UI Channel 20
4.1 | Transmitter Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2 | Transmitting UI Files to IRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.2.1 | Sample Manifest File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.2 | Sample Form Data File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.3 | Retrieving Acknowledgment from IRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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4.4 | Transmitter IRS Form Data File Specification. . . . . . . . . . . . . . . . . . . . . . . . . 32
4.5 | Transmitting Information Returns to IRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.5.1 | Validation of IRS Form Data File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.5.2 | Processing of IRS Form Data File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.6 | Retrieving Status of the Transmission through UI. . . . . . . . . . . . . . . . . . . . . . 34
4.7 | IRS Error Data File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.8 | UI Channel TY2017, TY2018, TY2019, TY2020, TY2021, TY2022,TY2023, TY2024, TY2025 and TY2026 Schemas. . . . . . . . . . . . . . 38
4.9 | 4.9 Calculate AttachmentByteSizeNum for TY2017,TY2018, TY2019, TY2020, TY2021, TY2022, TY2023, TY2024, TY2025 and TY2026. . . . . . . . . . . . . . . 38
Section 5 Transmitting IRS ACA Form Data File and Retrieving Acknowledgment via the ISS-A2A Channel 40
5.1 | Message Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.2 | Basic SOAP Message Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.2.1 | Creating the SOAP Envelope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.2.2 | SQL Injection in the SOAP Message. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.3 | SOAP Header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.3.1 | WS-Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.3.2 | ACA Transmitter Business Header Elements . . . . . . . . . . . . . . . . . . . . . 53
5.3.3 | ACA AIR Transmission Manifest. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.4 | SOAP Body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.4.1 | Message Attachment File Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.4.2 | Message Attachment Content Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.5 | ISS-A2A Web Services Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.5.1 | Overview of Transmission and Submission. . . . . . . . . . . . . . . . . . . . . . . 56
5.5.2 | IRS-ACA Submit Transmission Request Message. . . . . . . . . . . . . . . . . 58
5.5.3 | IRS-ACA Retrieve Acknowledgement Request Message. . . . . . . . . . . . 60
5.5.4 | A2A Channel TY2017, TY2018, TY2019, TY2020,TY2021, TY2022, TY2023, TY2024, TY2025 and TY2026 Schema/WSDL Guidance. . . . . . . . . . . 62
Guide for Electronically Filing ACA Information Returns for Software Developers and Transmitters III
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Section 6 Identifying Transmissions and Records 64
6.1 | Identifying the Transmission Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6.2 | Identifying the Transmission Status (Acknowledgement) . . . . . . . . . . . . . . . 66
6.3 | Receipt ID or UTID as Basis for Uniquely Identifying Transmissions and Records. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.3.1 | Uniquely Identifying Forms 1094 within a Transmission. . . . . . . . . . . . . 70
6.3.2 | Uniquely Identifying Forms 1095 within a Transmission. . . . . . . . . . . . . 71
6.4 | Identifying Records with Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.5 | Corrections and Replacements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.5.1 | The Correction Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.5.2 | Transmitting Corrections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.5.3 | Transmitting Form 1094-C Corrections (Authoritative Transmittals Only).75
6.5.4 | Transmitting Forms 1095-B or 1095-C Corrections . . . . . . . . . . . . . . . . 76
6.5.5 | Transmitting Forms 1094-C and Forms 1095-C Corrections. . . . . . . . . 76
6.6 | Rejected Transmissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.6.1 | Transmissions Rejected by IRS Portal. . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.6.2 | Transmissions/Submissions Rejected by AIR. . . . . . . . . . . . . . . . . . . . . 77
6.7 | Replacement Process - Transmitting Replacements. . . . . . . . . . . . . . . . . . . 78
6.7.1 | Replacement Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.7.2 | Replacement Submission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Section 7 Data Mapping for ISS-UI Services/ISS-A2A Web Services 86
7.1 | Data Mapping – Message Data Boundary. . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
7.2 | Data Mapping – Form Data Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Section 8 Example ISS-A2A Web Service Messages 106
8.1 | Transmitter Services SOAP Message Elements. . . . . . . . . . . . . . . . . . . . . . 106
8.1.1 | IRS-ACASubmitService SOAP Request Message – Manifest Header (ACAGetTransmitterBulkRequestService.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . 106
8.1.2 | IRS-ACASubmitService SOAP Request Message – Form Data File (ACAGetTransmitterBulkRequestService.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . 108
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8.1.3 | IRS-ACASubmitService SOAP Response Message (ACAGetTransmitterBulkRequestService.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . 112
8.1.4 | IRS-ACAAckngService SOAP Request Message (ACAGetTransmitterBulkRequestStatus.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.1.5 | IRS-ACAAckngService SOAP Response Message – Manifest Header (ACAGetTransmitterBulkRequestStatus.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.1.6 | IRS- ACAAckngService SOAP Response Message – Error Data File (ACAGetTransmitterBulkRequestStatus.wsdl). . . . . . . . . . . . . . . . . . . . . . . . . . 114
Section 9 General Philosophy on Data Elements in XML Schemas 116
Section 10 Validating a Transmission against XML Schema 118
10.1 | Structure of Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
10.2 | Validation of Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
10.3 | Validating the Transmission Envelope Including Contents. . . . . . . . . . . . . 119
10.4 | How Errors are Reported. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Section 11 Reporting Business Rule Validation Errors 123
11.1 | Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
11.2 | Data Validation and Error Reporting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
11.2.1 | Processing Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
11.2.2 | Error and Business Rule Library. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Section 12 SOAP Fault Response Messages 126
12.1 | ISS-Portal Error Codes and Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Section 13 Appendix A - Acronyms and Abbreviations 142
Section 14 Appendix B - AIR Transmission Checklist (A2A) for TY2026 144
Section 15 Appendix C - IR Transmission Checklist (UI) for TY2026 150
Guide for Electronically Filing ACA Information Returns for Software Developers and Transmitters V
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List of Tables
Table 3-1: Prefix and Target Namespaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 3-2: Transmission Manifest XML Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4-1: Forms to XML Schema File Mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 4-2: Transmission Processing Status Included in Acknowledgement. . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 5-1: Characters not allowed due to SQL Injection Concerns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5-2: IRS Authorized Certificate Issuing Authorities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5-3: Transmitter Business Header Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5-4: Transmission SOAP Message Binding – SOAP Request Message Header. . . . . . . . . . . . . . . . . . . 58
Table 5-5: Transmission SOAP Message Binding – SOAP Request Message Body. . . . . . . . . . . . . . . . . . . . . 59
Table 5-6: Transmission SOAP Message Binding – SOAP Response Message Header. . . . . . . . . . . . . . . . . . 59
Table 5-7: Transmission SOAP Message Binding – Soap Response Message Body. . . . . . . . . . . . . . . . . . . . 59
Table 5-8: Status Request SOAP Message Binding – SOAP Request Message Header . . . . . . . . . . . . . . . . . 60
Table 5-9: Status Request SOAP Message Binding – SOAP Request Message Body. . . . . . . . . . . . . . . . . . . 61
Table 5-10: Status SOAP Message Binding – SOAP Request Message Header. . . . . . . . . . . . . . . . . . . . . . . . 61
Table 5-11: Transmission SOAP Message Binding – Soap Response Message Body. . . . . . . . . . . . . . . . . . . 61
Table 6-1: Transmission Type Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Table 6-2: Unique Submission Identifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 6-3: Unique Record Identifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 7-1: Form 1094-1095 B and C Transmission SOAP Request Header – ACA Business Header . . . . . . . 87
Table 7-2: Form 1094-1095 B and C Transmission SOAP Request Manifest Header. . . . . . . . . . . . . . . . . . . . 87
Table 7-3: Form 1094-1095 B and C Transmission SOAP Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Table 7-4: Form 1094-1095 B and C Acknowledgement SOAP Request to check the Status of the Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Table 7-5: Form 1094-1095 B and C Transmission SOAP Response Header. . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Table 7-6: Form 1094-1095 B and C Transmission SOAP Response Header – ACA Business Header. . . . . . 91
Table 7-7: Form 1094-B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Table 7-8: Form 1095-B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Table 7-9: Form 1094-C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Table 7-10: Form 1095-C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Guide for ACA Information Returns Submission Composition and Reference Guide. . . . . . . . . . . . . . . . . . 123
Table 12-1: Portal Error Codes (Fault Codes) for Tax Years 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 and 2026. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Guide for Electronically Filing ACA Information Returns for Software Developers and Transmitters. . . . . 149
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List of Figures
Figure 2-1: External Clients and IRS AIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3-1: Structure of IRS Form Data File [B and C]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 3-2: Unique Transmission Identifier (UTID). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 3-2: Unique Transmission Identifier (UTID). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 3-3: Unique Submission Identifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 3-4: Unique Record Identifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 4-1: ISS-UI Channel Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 4-2: ISS-UI Channel Transmission Submission Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 4-3: ISS-UI Channel Transmission Submission Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 4-4: Sample Manifest File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 4-5: Sample 1094-1095 B Form Data File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 4-6: Transmission Status Search Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 4-6b: Transmission Status Search Page (UTID). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 4-7: A2A Check Status using UTID Request. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 4-8: A2A Check Status using UTID Response to Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 4-9: ISS-UI Channel Transmission Status Results Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 4-10: Example of Acknowledgement via ISS-UI Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 4-11: Error Data XML File. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 5-1: Basic SOAP Message Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 5-2: High Level Form schema structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 5-3: ACA Binding – ACAGetTransmitterBulkRequestService.wsdl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 5-4: ACA Binding – ACAGetTransmitterBulkRequestStatus.wsdl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 6-1: Identifying the Transmission Status Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Figure 6-3: Sample AIR ISS-A2A Transmission Intake Response Message . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 6-4: Sample AIR ISS-UI Transmission Intake Response Message. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 6-5: Submission Id is Required for Every Form 1094 in the Transmission. . . . . . . . . . . . . . . . . . . . . . . 70
Figure 6-6: Form 1094-C XML Schema Including RecordId. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Figure 6-7: Reference Records to be Corrected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Figure 6-8: Replacing a Rejected Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Figure 6-9: Visual depicting the first-rejected submission in a chain of rejections that should be replaced. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Guide for Electronically Filing ACA Information Returns for Software Developers and Transmitters VII
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