TA1 `001`: ISA and IEA control numbers don't match

The partner rejected the whole interchange before reading a single transaction, because the envelope's start (ISA) and end (IEA) don't agree. You'll get a TA1, and often no 997 at all.

What you see

TA1*000000417*261021*1430*R*001~

Reading it: TA101 = the ISA13 you sent, TA102/TA103 = your ISA date and time, TA104 R = rejected, TA105 001 = The Interchange Control Number in the Header and Trailer Do Not Match.

Related TA105 codes: 021 = Invalid Number of Included Groups Value (IEA01 is wrong), and 025 = Duplicate Interchange Control Number.

What it means

ISA13 (element I12) is a 9-digit number you assign. IEA02 must be exactly the same 9 digits. IEA01 must equal the number of GS/GE functional groups inside the interchange.

Why it happens

The trailer is written without zero-padding (IEA*1*417) while ISA13 is padded (000000417).
The counter is incremented between writing ISA and IEA.
Files were merged or split by hand or by a script, so IEA01 no longer matches the number of GS groups.
A file was resent with the same ISA13 (code 025 at partners that check for duplicates).

The exact fix

Set IEA02 to the exact 9-digit value in ISA13.
Set IEA01 to the number of GS segments in the interchange (usually 1).
When resending, assign a new ISA13 (and update IEA02 to match) so you don't trigger a duplicate reject.

Before and after

Rejected

ISA*00*          *00*          *02*XMPL           *ZZ*BROKERX        *261021*1430*U*00401*000000417*0*P*>~
GS*QM*XMPL*BROKERX*20261021*1430*417*X*004010~
...
GE*1*417~
IEA*1*417~

Accepted

ISA*00*          *00*          *02*XMPL           *ZZ*BROKERX        *261021*1430*U*00401*000000417*0*P*>~
GS*QM*XMPL*BROKERX*20261021*1430*417*X*004010~
...
GE*1*417~
IEA*1*000000417~

Stop it happening again

Generate ISA13 once per interchange, store it, and write IEA02 from that stored value.
Keep the interchange counter increasing and never reuse it, including for resends.
Count GS segments to set IEA01 rather than hard-coding 1.

Not sure this is your error?

Paste your 997, TA1, rejected file, or the broker's error email into the free EDI Reject Checker. It decodes every AK3/AK4/AK5/AK9 and TA1 code and checks counts, control numbers, and dates in seconds. It runs in your browser, so nothing is uploaded.

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References

TA1 Interchange Acknowledgment, 004010
Element I18, Interchange Note Code (001, 021, 025)
ISA Interchange Control Header (ISA13 is N0, exactly 9 digits)
X12, Transaction Sets

TA1 001: ISA and IEA control numbers don't match