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DPI / DAC7 submission over CCN2

What has happened with the transmission of 2025 DAC7 data, and where the matter currently stands.
Meeting30 July 2026
Prepared byState Tax Inspectorate (VMI)
Republic of Lithuania
ReferencesSD1519739 / IM1003542
SD1530878 / IM1012664
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The situation in one slide

Transmission worked in 2024 and 2025. We changed our file structure — and it stopped.

2024–25
DAC7 data submitted successfully in both years.
~200 MB
Uncompressed XML after moving to one file per Member State.
0
HTTP responses returned by the gateway at that size.

The technical question is still open

Raised with ITSM on 1 July. Four weeks later none of our five questions has been answered — the entire exchange has been about how to deliver a 95 MB sample file to a support desk that cannot receive it.

The obligation is blocked

No 2025 DAC7 data has reached the other 26 Member States, and Lithuania cannot supply the statistics TAXUD has requested since May.

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Background · 01

This exchange worked for two years

  • DAC7 submission to Member States was implemented in 2024.
  • Files for reporting years 2023 and 2024 were transmitted successfully.
  • In 2025 the contractor's design produced 6,716 separate files delivered to 27 Member States.
  • All of them went through. The transport was never the problem.

Source: internal summary, Declaration Procedures Administration Division, 28 July 2026.

Why we changed it anyway

The 2025 design did not meet VMI needs, as it makes file management considerably harder.

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Background · 02

What changed on our side

2025Many small files per Member State — 6,716 in total. Easy for the gateway, hard for us.
→
2026Aggregation to one file per Member State, capped at 80,000 records per file.
→
ResultPayload grows to ~95 MB on disk, ~200 MB of uncompressed XML in the SOAP body.

Where the 80,000 cap came from

The cap of 80,000 records per file was derived by analogy with DAC2.

Where it stopped working

Files up to roughly 50 MB had previously been accepted. At the new size the gateway returns no response at all.

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The failure

The gateway takes everything, then says nothing

POST https://s2s.prod.ccn2.taxud:8441/CCN2.Service.Taxation.Default.AEOI_DAC7.InitialMessageBAS
  • TLS handshake completes against DG TAXUD PROD CA.
  • Full SOAP body is sent — 25.1 MB compressed, zero TCP retransmissions.
  • Gateway then closes the connection FIN/RST.
  • No 200. No 202. No 413. No SOAP fault. Nothing.
  • Identical with Content-Length and Transfer-Encoding: chunked.
  • Each attempt lasts ~21–23 seconds.

The 500 error on our side is a symptom

Our service fails because it is waiting for a response that never arrives.

{"status":500,"error":"Internal Server Error",
"path":"/initialMessage/send/30440"}

Contractor assessment: processing on the CCN2 side takes too long and the socket times out.

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What we asked · 1 July 2026

Five questions. None answered yet.

  1. What is the maximum accepted message size — compressed and uncompressed — for InitialMessageBAS in production?
  2. Does the gateway log this request? If so, what error or status is recorded when it closes the connection without responding?
  3. Is splitting one DAC7 InitialMessage across multiple SOAP calls supported? If so, what payload per call, and are sequencing or correlation identifiers required?
  4. Is Transfer-Encoding: chunked supported on port 8441, or is Content-Length mandatory?
  5. What do the CCN2 logs show for our attempts on 25 June at ~10:20 and ~12:20 UTC?

Submitted to ITSM on 1 July 2026 as ticket SD1519739. None has been answered to date.

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Timeline · April to June

Two and a half months before the ticket existed

17 Apr
Submission fails with CCN2-ROU-1004 — "The routing information is invalid".
22 Apr
Correct channel identified internally: DAC2/4/7/8 technical questions go to taxation-support@itsmtaxud.europa.eu.
22 May
Commission advises that IT colleagues have replied, and requests Lithuanian 2025 statistics.
9 Jun
Routing error resolved. A 500 error persists due to increased payload size. We ask whether CCN2 imposes a size limit. Statistics cannot be supplied — nothing can be sent.
25 Jun
Two attempts to InitialMessageBAS. Both end with the connection closed and no response.
28 Jun
500 recorded against LT2024NL-DPI-30440.
29 Jun
Commission replies after 20 days. The size-limit question is not answered — we are directed to ITSM support.
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Timeline · handover

Two days spent finding out how to open a ticket

  • The officer who previously handled this area had left the division.
  • The ITSM procedure was not part of the handover — no access, no process, no practice for attaching files.
  • Both colleagues with the relevant experience were on leave.
  • The address was eventually recovered from earlier correspondence.

Once we had the address

Received at 12:20 on 1 July.
Request sent at 12:32 the same day.

12 min
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Timeline · ticket SD1519739

The ticket never reached the technical question

1 Jul
Request sent 12:32. Registered 12:48 as SD1519739, priority 3 (Medium), incident IM1003542.
2 Jul
ITSM asks for the message ID of the test performed.
13 Jul
LT2024NL-DPI-30440 provided. ITSM then asks for the file itself.
14 Jul
File obtained (95 MB; 3 MB compressed). Send fails — 550 5.7.0 Message Size Violation. ITSM proposes FTP.
15 Jul
FTP requires a dedicated account and a separate ticket. On confirmation, SD1519739 is placed on hold. A signed access form is required.
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Timeline · ticket SD1530878

A second ticket, to obtain access to deliver a file

20 Jul
Form guidance received and form completed. Manager approval given — first in Lithuanian, then re-issued in English at ITSM's request, then re-sent to a different mailbox at ITSM's request.
20 Jul
SD1530878 / IM1012664 registered. Form reported as incorrectly completed; resubmitted and confirmed as being processed — without stating what had been wrong.
23 Jul
ITSM asked for the expected processing timeline and credential delivery date.
28 Jul
Credentials arrive as a password-protected archive — blocked by our own mail filter. Being resolved.
2
Tickets open for one technical question.
3
Times the same approval had to be re-sent.
0
Technical questions answered to date.
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Where we are today · 28 July 2026

Current status

TechnicalSD1519739 / IM1003542 on hold
Reactivated only once the file is delivered.
FTP accessSD1530878 / IM1012664 in progress
Account appears created; credentials blocked in transit.
Priority3 (Medium) on both — never challenged.
DataNo 2025 DAC7 submissions to any Member State.

Remaining chain

  • Release the blocked email, obtain credentials.
  • Upload the XML and the TCP captures to ftp.itsmtaxud.priv.
  • Notify ITSM to reactivate SD1519739.
  • Wait for answers to questions 1–5.
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Impact and risks

What is at stake

Legal obligation

2025 DAC7 data has reached none of the other 26 Member States. Lithuania cannot supply the statistics TAXUD has requested since May.

Reporting cycle

The draft 2026 DAC7 report was circulated on 24 July with comments due by end of August and an SG AEOI meeting in September. Lithuanian figures are still missing.

Contractor availability

The contract with Novian is approaching its end while the cause remains unidentified. Losing that expertise would make further analysis considerably harder.

Approver availability

The manager who signed the FTP access form is on leave from 27 July to 17 August. A deputy will be needed if ITSM requires a clarification or a revised form.

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Outstanding

What is still open

  • The five technical questions submitted on 1 July remain unanswered.
  • SD1519739 / IM1003542 is on hold, to be reactivated once the sample file has been delivered.
  • The ITSM registration notice states that the assigned priority may be reviewed if justification is provided. No such request has been made on either ticket.
  • The reported file size is inconsistent — ~200 MB of uncompressed XML in the original request against 95 MB for the file provided. To be clarified before the investigation begins.
  • ITSM did not specify what was incorrectly completed in the first version of the access form.
  • A deputy approver is needed while the responsible manager is on leave, 27 July to 17 August.
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Reference

Identifiers

Technical ticketSD1519739 / IM1003542
FTP ticketSD1530878 / IM1012664
Message ref.LT2024NL-DPI-30440
FileLT2024NL-DPI-30440.xml
95 MB · 3 MB as .7z
Captureschunked.pcap
non-chunked.pcap
FTP hostftp.itsmtaxud.priv
147.67.18.8
Attempts25 Jun 2026, 10:20 & 12:20 UTC
ClientApache CXF 4.2.2, mutual TLS
https://s2s.prod.ccn2.taxud:8441/CCN2.Service.Taxation.Default.AEOI_DAC7.InitialMessageBAS

Full written overview available on request — State Tax Inspectorate, Republic of Lithuania.

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