ANSI X12 837P - 5010 ISA & IEA Interchange Control Header and Trailer

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September 22, 2025

The ISA (Interchange Control Header) and IEA (Interchange Control Trailer) segments are the opening and closing “envelope” of an X12 837 (5010) professional claim file. Together, they define the start and end of the interchange and ensure that the data between them is processed as a single unit. The ISA establishes sender/receiver details, control numbers, delimiters, and usage indicators, while the IEA closes the interchange and provides the count of functional groups inside.

The ISA/IEA pair is mandatory and always appears exactly once per interchange. Because the ISA segment is fixed length, each data element must be padded to its required length (for example, ISA06 and ISA08 must be exactly 15 characters). Any mismatch between ISA13 and IEA02 or incorrect padding will cause interchange rejections.

Sample 837P (5010) – ISA / IEA Interchange Control Envelope

> Interchange Control Header & Trailer
  • ISA*00*          *00*          *ZZ*SENDERID       *ZZ*RECEIVERID     *250918*0535*^*00501*000000011*1*P*:~
  • GS*HC*SENDERCODE*RECEIVERCODE*20250918*0535*10022*X*005010X222A1~
    • ST*837*0001*005010X222A1~
    • ... (claims detail segments) ...
    • SE*39*0001~
    GE*1*10022~
  • IEA*1*000000011~

In this example:

  • ISA13 – Interchange Control Number is 000000011, which matches IEA02 at the end.
  • IEA01 – Contains the count of functional groups (GS/GE pairs) in this interchange (here, 1).
  • IEA02 – Must exactly match ISA13, forming a control pair to validate file integrity.

Reminder: The ISA/IEA envelope should always properly match. Many clearinghouses will reject an entire interchange if the control number sequence is out of sync or if IEA01 does not reflect the correct count of GS segments.

HIPAA Guide – 837P [5010]

[Mandatory]

Segment Field Name Definition
ISA 01 Authorization Information Qualifier Usually 00 when not used.
CodeDefinition
00No Authorization Information Present (No Meaningful Information in I02)
03Additional Data Identification
ISA02Authorization Information10 characters; blank-padded when not used.
ISA 03 Security Information Qualifier
CodeDefinition
00No Security Information Present (No Meaningful Information in I04)
01Password
ISA04Security Information10 characters; blank-padded when not used.
ISA 05 Interchange ID Qualifier (Sender) Qualifier for ISA06 (Sender ID).
CodeDefinition
01Duns (Dun & Bradstreet)
14Duns Plus Suffix
20Health Industry Number (HIN) — Code Source 121: Health Industry Identification Number
27Carrier Identification Number as assigned by Health Care Financing Administration (HCFA)
28Fiscal Intermediary Identification Number as assigned by Health Care Financing Administration (HCFA)
29Medicare Provider and Supplier Identification Number as assigned by Health Care Financing Administration (HCFA)
30U.S. Federal Tax Identification Number
33National Association of Insurance Commissioners Company Code (NAIC)
ZZMutually Defined
ISA06Interchange Sender ID15 characters, left-justified and space-padded.
ISA 07 Interchange ID Qualifier (Receiver) Qualifier for ISA08 (Receiver ID).
CodeDefinition
01Duns (Dun & Bradstreet)
14Duns Plus Suffix
20Health Industry Number (HIN) — Code Source 121: Health Industry Identification Number
27Carrier Identification Number as assigned by Health Care Financing Administration (HCFA)
28Fiscal Intermediary Identification Number as assigned by Health Care Financing Administration (HCFA)
29Medicare Provider and Supplier Identification Number as assigned by Health Care Financing Administration (HCFA)
30U.S. Federal Tax Identification Number
33National Association of Insurance Commissioners Company Code (NAIC)
ZZMutually Defined
ISA08Interchange Receiver ID15 characters, left-justified and space-padded.
ISA09Interchange DateDate the file was created, format YYMMDD (e.g., 250918).
ISA10Interchange TimeTime the file was created, format HHMM (e.g., 0535).
ISA 11 Repetition Separator Single character that separates repeated occurrences of data elements within a segment (e.g., ^).
ISA12Interchange Control Version Number00501 for X12 5010.
ISA13Interchange Control Number9-digit control number; must match IEA02 exactly.
ISA 14 Acknowledgment Requested
CodeDefinition
0No Acknowledgment Requested
1Interchange Acknowledgment Requested (TA1)
ISA 15 Usage Indicator
CodeDefinition
PProduction Data
TTest Data
ISA16Component Element SeparatorSingle character used to separate sub-elements (e.g., :).
IEA01Number of Included Functional GroupsCount of GS/GE pairs within the interchange (e.g., 1).
IEA02Interchange Control NumberMust equal ISA13 to confirm envelope integrity (e.g., 000000011).

Note: The ISA and IEA segments form a matched pair. ISA13 and IEA02 must always match, and IEA01 must equal the number of GS segments between ISA and IEA. Always validate these when troubleshooting rejected EDI files.

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