ED14 - Authority Interface Practice: ELSTER, DE-Mail, eXTra - Mediation by GitCover

Problem

Many authority interfaces are legally regulated, but in practice barely usable for laypeople:

ELSTER: complex, error-prone - the ELSTER interface requires certificates, XML formats, client software - a hurdle for laypeople
DE-Mail: discontinued - DE-Mail was planned as a secure communication channel with authorities, but is officially discontinued (last provider on 31.12.2026). Archived emails in discontinued systems are no longer accessible - a GoBD-relevant retention problem
eXTra: unknown - the eXTra format (SV data) is for payroll offices, not for entrepreneurs - but during a DRV audit it suddenly becomes relevant
Z3 data carrier: specialist knowledge - the GoBD-compliant Z3 export requires specialist software or manual preparation
Interface errors: not documented - if ELSTER or DE-Mail fail, the error is not logged in the repo - the evidence "I tried" is missing
Regulation binding: not assigned - every interface transmission is bound to a regulation (e.g. LStA → § 41a EStG), but this assignment is not documented

Core message

The GitCover harness mediates between external systems and risk-affine regulations:

ELSTER mediation - LStA, UStA, LSt certificate via ELSTER interface; receipt as evidence with sidecar
DE-Mail: discontinued - migration required - historical DE-Mails must be migrated to the repo before shutdown as EML + SHA-256 + sidecar; archived emails in discontinued systems are no longer accessible - GoBD retention problem
eXTra/euBP export - SV data in eXTra format exportable for DRV audits
Z3 data carrier export - GoBD-compliant Z3 export for FA external audits (git bundle as self-contained archive)
Interface error logging - errors/abortions of external systems are logged as repo events
Regulation binding - every interface operation is mapped to the risk-affine regulation

Compliance by Design: The harness does not hide the complexity of authority interfaces - it documents it. Every transmission, every receipt, every error is captured traceably in the repo.

The authority interface landscape

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD U["Unternehmer E1"] U --> H["GitCover-Harness"] H --> EL["ELSTER"] H --> DM["DE-Mail (eingestellt)"] H --> EX["eXTra/euBP"] H --> Z3["Z3-Datenträger"] EL --> FA["Finanzamt"] DM --> BH["Behörden (diverse)"] EX --> DRV["DRV (SV-Prüfung)"] Z3 --> AP["Finanzamt (Außenprüfung)"] style U fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style H fill:#10A987,stroke:#0A7F5C,color:#FBFAF7 style EL fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style DM fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style EX fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style Z3 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style FA fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style BH fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style DRV fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style AP fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33

Interface	Purpose	Complexity	GitCover mediation
ELSTER	LStA, UStA, LSt certificate, e-invoice viewer	high (certificate, XML, client)	receipt as evidence with sidecar
DE-Mail	Secure communication with authorities	discontinued (last provider 31.12.2026)	migration: EML + sidecar into repo; warning
eXTra/euBP	SV data for DRV audits	high (specialist format)	export from repo data
Z3 data carrier	GoBD-compliant export for FA external audit	high (specialist software)	git bundle as self-contained archive

ELSTER mediation

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD L["LStA/UStA berechnet"] L --> E["ELSTER-Übermittlung"] E --> Q["ELSTER-Quittung"] Q --> S["Quittung als Beleg mit Sidecar"] S --> R["Repo: LStA-Eintrag mit source_sha256"] R --> V["Vorschriften-Binding: § 41a EStG"] E -->|Fehler| F["Fehler-Logging im Repo"] F --> FR["Repo-Ereignis: ELSTER-Fehler"] style L fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style E fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style Q fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style S fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style R fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style V fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style F fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style FR fill:#FDBA74,stroke:#C2410C,color:#0F1B33

Step	Action	GitCover implementation
LStA calculated	Payroll tax registration from payroll	JSON artefact in repo (see ED11)
ELSTER submission	Electronically via ELSTER (certificate required)	harness calls ELSTER
Receipt	ELSTER confirms transmission	receipt as evidence with sidecar
Repo entry	LStA with `source_sha256` on receipt	`tags: ["lsta", "§41a-estg"]`
Regulation binding	LStA → § 41a EStG	`vorschrift: "§41a-estg"` in artefact
Error logging	ELSTER error is logged	repo event with error description

Regulation binding: Every interface operation is mapped to the risk-affine regulation - e.g. LStA → § 41a EStG, UStA → § 18 UStG, LSt certificate → § 41b EStG. This makes it traceable which regulation was fulfilled by which transmission.

DE-Mail - discontinued: migration and archival consequences

DE-Mail is officially discontinued. The project is considered failed. The last provider (FP Digital Business Solutions GmbH) will shut down the service on 31.12.2026 - after that DE-Mail is no longer usable and archived emails in these systems are no longer accessible.

Event	Date	Source
Telekom discontinues De-Mail	31.08.2022	"due to lack of economic viability"
1&1 De-Mail GmbH discontinues	07.02.2025	service no longer reachable
§ 130a ZPO repealed	22.12.2025	De-Mail as secure transmission path abolished (BGBl. 2025 I Nr. 349)
Federal administration discontinues	July 2024	mandatory use ended
Last provider (FP Digital) discontinues	31.12.2026	"Thus De-Mail is history"
Bundesrechnungshof 2021	2021	2011-2020: ~6,000 De-Mails from authorities, savings ~3,500 EUR, costs >= 6.5 Mio. EUR
CCC criticism	2013	Linus Neumann (30C3): "Bullshit made in Germany - intentionally built insecure"

DE-Mail is history: The last provider (FP Digital Business Solutions GmbH) will shut down the service on 31.12.2026. The statutory recognition as a secure transmission path (§ 130a Abs. 4 Nr. 1 ZPO) was repealed on 22.12.2025. The federal administration ended mandatory use in July 2024. The Bundesrechnungshof summarised in 2021: 6.5 Mio. EUR costs for ~3,500 EUR savings. A successor, "European Business Wallet (EBW)", is planned.

Consequences of archived emails in discontinued systems

When a DE-Mail provider shuts down its service, immediate GoBD-relevant retention problems arise:

Problem	Consequence	GoBD reference
Mailbox no longer accessible	emails can no longer be retrieved	§ 146 Abs. 5 AO ("available at any time")
Provider-side deletion	after shutdown data is deleted	§ 147 Abs. 1 AO (retention obligation 6 years)
No export possible	if the provider offers no export function, data is irretrievably lost	GoBD Rz. 146 (traceability)
Evidentiary value lost	DE-Mail-specific confirmations (dispatch/delivery confirmation) can no longer be verified	loss of evidence in authority dispute
No forensic preservation	a layperson can hardly forensically upgrade the authenticity of old emails afterwards - without provider infrastructure the verification data (signature check, timestamp server, provider logs) is missing	evidentiary downgrade to "mere PDF copy"
Retention period still running	emails from 2024 must be retained until 31.12.2030 - but the system is gone in 2026	GoBD violation through unavailable retention

Forensic preservation - barely recoverable: DE-Mail-specific evidentiary features (qualified electronic signature of the dispatch and delivery confirmation, provider timestamp, integrity hash) can only be verified within the running provider infrastructure. After shutdown these verification data are no longer available. A layperson cannot subsequently verify an exported EML file for its DE-Mail-specific authenticity - signature checking fails for lack of the provider certificate, the timestamp server is offline, the provider logs are deleted. The email loses its status as "legally binding DE-Mail communication" and degenerates to a mere PDF copy with strongly reduced evidentiary value. Subsequent forensic preservation by an expert would be theoretically possible, but practically barely feasible - the required provider infrastructure data no longer exist.

Critical warning - migrate before shutdown: Entrepreneurs who still have a DE-Mail mailbox must before shutdown export all relevant emails as EML files and migrate them into the Git repo (EML + SHA-256 + sidecar). After shutdown an export is no longer possible - the data is irretrievably lost. This is a GoBD violation if the retention period is still running (6 years from year-end, § 147 Abs. 1 Nr. 2/3 AO).

GitCover migration: DE-Mail -> repo

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart LR D["DE-Mail-Postfach (eingestellt)"] D --> EX["Export vor Abschaltung"] EX --> EML["EML-Dateien"] EML --> SH["SHA-256 pro EML"] SH --> SC["Sidecar .v7g.md pro EML"] SC --> R["Repo: sources/korrespondenz/"] R --> OK["GoBD-konform archiviert"] D -->|nach Abschaltung| LOST["Daten unwiederbringlich verloren"] LOST --> V["GoBD-Verstoß"] style D fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style EX fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style EML fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style SH fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style SC fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style R fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style OK fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style LOST fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style V fill:#FDBA74,stroke:#C2410C,color:#0F1B33

Step	Action	Deadline
Export	export all relevant emails as EML	before shutdown (at the latest 31.12.2026)
SHA-256	compute hash per EML file	on migration
Sidecar	`.v7g.md` per EML with classification	on migration
Storage	EML + sidecar in `sources/korrespondenz/`	on migration
Verification	check completeness (number of emails)	after migration

Practical tip: The migration should be carried out immediately, not just before shutdown. Providers may restrict the service early (e.g. no new registrations, restricted export). Those who wait risk data loss.

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart LR D["DE-Mail (eingestellt)"] D --> P["Gescheitert: 6,5 Mio EUR Kosten, ~3500 EUR Nutzen"] P --> W["Warnung: DE-Mail nicht nutzen"] W --> A["Alternative: ELSTER-Postfach"] D --> E["Eingehende Behörden-E-Mail (historisch)"] E --> AR["EML archiviert + Sidecar"] AR --> V["Absender-Verifikation (DKIM/SPF)"] style D fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style P fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style W fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style A fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style E fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style AR fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style V fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33

Aspect	Problem	GitCover solution
Status	DE-Mail officially discontinued (last provider 31.12.2026)	warning: do not use; migration required
Cost/benefit	6.5 Mio. EUR costs, ~3,500 EUR savings (Bundesrechnungshof)	git bundle and ELSTER mailbox are free
Security	"intentionally built insecure" (CCC, Linus Neumann 2013)	Git + GPG + SHA-256
Statutory recognition	§ 130a ZPO repealed on 22.12.2025	no longer relevant
Archiving	archived emails in discontinued systems no longer accessible	migration: EML + SHA-256 + sidecar into repo
Retention period	emails from 2024 must be retained until 2030 - system gone in 2026	GoBD violation for non-migrated data
Successor	European Business Wallet (EBW) planned	open; GitCover independent

DE-Mail disaster mitigation: The harness warns on use of DE-Mail (if historical mailboxes still exist) and recommends immediate migration of all relevant emails as EML + sidecar into the repo. After shutdown (at the latest 31.12.2026) the data is irretrievably lost - a GoBD violation if the retention period is still running. As an alternative for future communication: ELSTER mailbox for tax topics, regular email + sidecar archiving for correspondence.

eXTra/euBP export and Z3 data carrier

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD R["Repo-Daten (JSON, Sidecars)"] R --> EX["eXTra-Export"] R --> Z3["Z3-Export (git bundle)"] EX --> DRV["DRV-Prüfung: SV-Daten"] Z3 --> FA["FA-Außenprüfung: GoBD-Daten"] EX --> F1["Format: eXTra V3.4.0"] Z3 --> F2["Format: git bundle + Manifest"] style R fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style EX fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style Z3 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style DRV fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style FA fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style F1 fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style F2 fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33

Export	Purpose	Format	Recipient
eXTra/euBP	SV data for DRV audit	eXTra V3.4.0 (XML)	DRV
Z3 (git bundle)	GoBD data for FA external audit	git bundle + manifest + static web (Z3+)	FA

Practical example: The DRV requests SV data in eXTra format during a Betriebsprüfung. The harness exports the relevant payroll and SV data from the repo as eXTra XML. The FA requests GoBD-compliant data (Z3) during an external audit - the harness generates a git bundle + static web (Z3+, see ED04). Both exports can be generated from the structured repo data (JSON, sidecars) - no manual preparation needed.

Interface error logging

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD S["Schnittstellen-Aufruf (ELSTER, DE-Mail)"] S --> OK["Erfolg: Quittung + Sidecar"] S --> ERR["Fehler: Abbruch, Timeout, Formatfehler"] ERR --> L["Fehler-Logging im Repo"] L --> E["Repo-Ereignis: Schnittstellen-Fehler"] E --> N["Nachweis: Fehler nicht verschuldet"] style S fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style OK fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style ERR fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style L fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style E fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style N fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33

Event	Action	GitCover implementation
Success	receipt archived	evidence with sidecar, `source_sha256` in artefact
Error	error logged	repo event with error description, timestamp, regulation
Evidence	"error not self-inflicted"	repo event as evidence during audit

Important - liability shift: If an interface fails (e.g. ELSTER timeout on the 10th of the month), the error logging in the repo documents that the entrepreneur tried to transmit in time. This is evidence under § 152 AO (late payment surcharge)

the entrepreneur can argue that the error was not in their sphere.

Risk leverage

Today (cheap)	Tomorrow (audit-proof)	Risk mitigated
ELSTER receipt as evidence with sidecar	transmission verifiable	late payment surcharge § 152 AO
DE-Mail warning + alternative	suitable channel chosen	loss of communication
eXTra export from repo data	SV data available for DRV audit	GoBD violation during DRV audit
Z3 export as git bundle	GoBD data available for FA audit	GoBD violation during FA audit
Interface error logging	evidence "tried"	liability shift on interface failure
Regulation binding	regulation per transmission documented	dispute of regulation fulfilment

Harness requirement (preview)

Derivable from ED14:

ID	Requirement	Priority
FA-12.1	ELSTER mediation: LStA, UStA, LSt certificate; receipt as evidence with sidecar	MUST
FA-12.2	DE-Mail/De-Mail bridge: EML + SHA-256 + sidecar; sender verification	SHOULD
FA-12.3	eXTra/euBP export: SV data in eXTra format for DRV audits	SHOULD
FA-12.4	Z3 data carrier export: GoBD-compliant Z3 export (git bundle)	SHOULD
FA-12.5	Interface error logging: errors as repo event	MUST
FA-12.6	Regulation binding: every operation mapped to risk-affine regulation	SHOULD
FA-12.7	DE-Mail disaster mitigation: warning on unsuitable channels	NICE
FA-12.8	Authority identifiers registry	MUST

The full requirement list in Harness-Anforderungen.md.

Sources

AO (§ 147 Abs. 6 - data access Z1/Z2/Z3, § 152 - late payment surcharge)
EStG (§ 41a - payroll tax registration, § 41b - LSt certificate)
UStG (§ 18 - VAT pre-registration, § 14 - e-invoice)
SGB IV (§ 28p - DRV Betriebsprüfung, § 28a - DEÜV registrations)
GoBD (BMF letter, Rz. 147 - verifiability, Z3 data access)
DE-Mail (Wikipedia, as of 14.08.2026) - "Thus De-Mail is history": Telekom 31.08.2022, 1&1 07.02.2025, § 130a ZPO 22.12.2025 repealed, federal administration July 2024, FP Digital 31.12.2026, Bundesrechnungshof 2021
BGBl. 2025 I Nr. 349 - Act repealing § 130a Abs. 4 Nr. 1 ZPO (DE-Mail)
Bundesrechnungshof annual report 2021 - DE-Mail: 6.5 Mio. EUR costs, ~3,500 EUR savings
CCC 30C3 2013 - Linus Neumann: "Bullshit made in Germany"
AFJD/agents/ (anonymised) - SSoT concept with ELSTER, interface error logging

Source topology and CDN reference links

Role	Location	Purpose
Primary / SSoT	git.gitcover.org/GCC	Canonical storage (GPG-signed, versioned)
Public OSS Mirror / CDN	codeberg.org/gitcover-commons	Read-only mirror; FLOSS discovery
Community Hub	github.com/gitcover-commons	Issues & discussions; source code reference to Codeberg

Note: This assignment of sources, mirror and community hub reflects the current state and may change. Please check the respective canonical source on gitcover.org for the current state.