ED07 - Retention Periods & Immutability: Git Hooks, Evidence Packages

Problem

GoBD and AO require long-term retention - but in practice implementation fails:

• "10 years? The cloud handles that." - many entrepreneurs believe the cloud software handles retention automatically - but on cancellation of the account the data is often no longer available (see ED01 pain point 6-7)
• Cloud account cancelled, data gone - the payroll account was paused, the old payroll accounts are only reactivatable at extra cost - GoBD violation (§ 146 Abs. 5 AO)
• Old software versions not reactivatable - the backups require the old software version, which is no longer installable
  • GoBD violation (§ 147 Abs. 2 AO: "immediately readable")
• No immutability - retroactively changed bookings without traceability - GoBD violation (Rz. 146)
• No evidence packages - during a field audit the auditor cannot be supplied with a data carrier (Z3) - GoBD violation (§ 147 Abs. 6 AO)
• Retention periods unknown - 10 years? 8 years? 6 years? Many entrepreneurs do not know the periods for their records

Core Statement

GoBD-compliant retention with Git means:

1. Git bundles are self-contained - no cloud account, no software license, no service provider - git clone is enough
2. Retention periods are documented in the repo - every artifact carries its period in the sidecar (obsolescence + period date)
3. Immutability through tags and protected branches - released states are cryptographically immutable
4. Evidence packages for period closings - git bundle + static web (Z3+) for auditors (see ED04)
5. Period check as Git artifact - checks/FRISTEN_CHECK.md warns of impending deadlines

Compliance by Design: Retention is not retroactive - it emerges through the choice of medium. Git bundles are self-contained and outlast every cloud lock, every software version change, every service provider cancellation.

Retention periods according to AO § 147

Important - start of period: The period begins with the end of the calendar year in which the last entry was made, the annual financial statement was prepared, the voucher was received or the record was made (§ 147 Abs. 4 AO). A booking of 15.08.2026 starts the period on 31.12.2026 - 10 years end on 31.12.2036.

Immutability through Git

Important - linear history: Only linear history without rewriting is GoBD-compliant. git rebase, git commit --amend and git push --force on main are prohibited. The pre-commit hook checks that no force pushes occur and that corrections are made as new commits with obsolescence marking.

Evidence packages for retention

A Tenant Evidence Package (see ED04 Z3+) for a fiscal year contains:

The safest retention: A USB stick with git bundle + static web + manifest is self-contained, offline, without IAM, without cloud account, without software license. It outlasts every service provider cancellation, every software version change, every cloud lock. That is the safest form of GoBD-compliant retention - because there are no dependencies.

Of course, the physical security of the USB stick must be considered (safe, fire protection, off-site backup).

Deadline management in the repo

checks/FRISTEN_CHECK.md

# Fristen-Check

## Vorlauf (bis 010926) - PRIO 1

- [ ] 200826: ELSTER-Organisationszertifikat anfordern
- [ ] 250826: Gefahrtarifstelle festlegen
- [ ] 300826: D&O-Versicherung GF-Haftung

## Aufbewahrungsfristen (laufend)

| Frist | Unterlagen-Typ | Endet | Status |
|---|---|---|---|
| 10 Jahre | Grundbuch FY2026 | 31.12.2036 | aktiv |
| 8 Jahre | E-Rechnungen FY2026 | 31.12.2034 | aktiv |
| 6 Jahre | E-Mails FY2026 | 31.12.2032 | aktiv |

Auto-warning on impending deadlines

Risk-Leverage

Harness requirement (preview)

Derivable from ED07:

The complete requirement list in Harness-Anforderungen.md.

Sources

• GoBD (BMF letter, Rz. 146 - immutability, Rz. 152 - retention periods)
• AO (§ 146 Abs. 5 - availability, § 147 - retention periods 10/8/6 years, § 147 Abs. 4 - start of period, § 147 Abs. 6 - Z3 data access)
• GitCover.Ledger/docs/02-Tenant-Evidence-Package.md - Tenant Evidence Package concept
• AFJD/agents/ (anonymized) - SSoT concept with deadline check, evidence packages

Source topology and CDN reference links

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.