ED08 - AO Fundamentals: Tax Procedure, Deadlines, Voluntary Disclosure

Problem

The Abgabenordnung (AO) is the foundation of German tax law - but in the SME sector it is largely unknown:

"AO? Never heard of it." - many entrepreneurs do not know the AO, although they work according to it daily (bookkeeping, deadlines, audits)
Missed deadlines - assessment periods, filing deadlines, limitation periods are missed because no one monitors them
Estimation as a threat - § 162 AO (estimation) is perceived as an abstract threat, without it being clear when it applies
Voluntary disclosure as a last resort - § 371 AO (voluntary disclosure) is known as an "emergency brake", but the requirements are complex
Field audit as a bogeyman - § 193 AO (field audit) is feared, without it being clear what it concretely means
No deadline monitoring - deadlines are in the calendar, but no one automatically warns before expiry

Core Statement

The AO regulates the tax procedure - and GitCover makes the obligations resulting from it machine-readable and automatically monitorable:

Deadlines as Git artifact - checks/FRISTEN_CHECK.md with auto-warning (see ED07)
Field audit as evidence package - Z3/Z3+ export (see ED04)
Avoid estimation through GoBD compliance - complete, traceable, immutable bookkeeping (see ED04-ED07)
Voluntary disclosure as a last resort - documented in the diary, if GoBD compliance cannot be established

Compliance by Design: The AO obligations are not fulfilled through retroactive review, but through **structural ** Git-native Compliance - deadline check, evidence packages, GoBD-compliant bookkeeping.

The Abgabenordnung (AO) - overview

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD AO["Abgabenordnung (AO)"] AO --> BV["Besteuerungsverfahren
§§ 78–133"] AO --> FB["Festsetzungs- und
Feststellungsverfahren
§§ 155–217"] AO --> AP["Außenprüfung
§§ 193–203"] AO --> SZ["Sanktionen
§§ 152, 162, 370, 379"] BV --> AN["Anmeldungen
(LStA, UStA, SV)"] FB --> FF["Festsetzungsfristen
§ 169 AO"] AP --> Z["Datenzugriff
Z1/Z2/Z3 (§ 147 Abs. 6)"] SZ --> VS["Verspätungszuschlag
§ 152 AO"] SZ --> SC["Schätzung
§ 162 AO"] SZ --> ST["Steuerstrafverfahren
§ 370 AO"] style AO fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style BV fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style FB fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style AP fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style SZ fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style AN fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style FF fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style Z fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style VS fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style SC fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style ST fill:#FDBA74,stroke:#C2410C,color:#0F1B33

AO area	Paragraphs	SME relevance
Tax procedure	§§ 78-133	Filings (LStA, UStA), cooperation duties
Assessment procedure	§§ 155-217	Assessment periods (§ 169), estimation (§ 162)
Field audit	§§ 193-203	Tax audit, data access Z1/Z2/Z3
Sanctions	§§ 152, 162, 370, 379	Late payment surcharge, estimation, tax criminal proceedings
Bookkeeping	§§ 140-147	GoBD foundation (see ED04-ED07)
Voluntary disclosure	§ 371	Emergency brake for tax evasion

Deadlines in the tax procedure

Monthly deadlines

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Lohnsteuer 10. : Lohnsteuer-Anmeldung § 41a EStG +5T : elektronisch +5 Tage section Umsatzsteuer 10. : Umsatzsteuer-Voranmeldung § 18 UStG section Sozialversicherung 3-letzter : SV-Beitragsnachweis § 23 SGB IV

Annual deadlines

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Steuererklärungen 31.07. : ESt / KSt / USt-Erklärung verl. : verlängert durch StB section Lohnsteuer-Bescheinigung 28.02. : Lohnsteuer-Bescheinigung § 41b EStG

Assessment periods (§ 169 AO)

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Regelfall 4J : Regelfrist § 169 Abs. 2 Nr. 2 AO section Erschwerung 5J : Bei leichtfertiger Verkürzung 10J : Bei Steuerhinterziehung

Deadline type	Deadline	Legal basis	GitCover monitoring
Payroll tax filing	10th of the following month (+5 days electronically)	§ 41a EStG	`FRISTEN_CHECK.md` + auto-warning
VAT pre-registration	10th of the following month	§ 18 UStG	`FRISTEN_CHECK.md` + auto-warning
SV contribution statement	third-last banking business day	§ 23 SGB IV	`FRISTEN_CHECK.md` + auto-warning
ESt/KSt/USt return	31.07. (extended by StB)	§ 149 AO	`FRISTEN_CHECK.md`
Payroll tax certificate	28.02. of the following year	§ 41b EStG	`FRISTEN_CHECK.md`
Assessment period (regular)	4 years	§ 169 Abs. 2 Nr. 2 AO	Retention period tracking
Assessment period (shortfall)	5 years (negligent) / 10 years (intentional)	§ 169 Abs. 2 Nr. 1/2 AO	Retention period tracking

Practical tip: The deadline check (checks/FRISTEN_CHECK.md) is maintained as a Git artifact and updated on every commit. The auto-warning (see ED07) warns 14 days before an authority deadline expires. This way no missed deadline is overlooked - and § 152 AO (late payment surcharge up to 25,000 EUR) is avoided.

Estimation (§ 162 AO) - and how Git avoids it

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart LR S["Schätzung § 162 AO"] S --> G1["Grund 1:
Daten nicht verwertbar
(unvollständig, verändert)"] S --> G2["Grund 2:
Buchführung nicht GoBD-konform"] S --> G3["Grund 3:
Unternehmer liefert keine Auskunft"] G1 --> R["FA schätzt die Besteuerungsgrundlagen
oft zuungunsten des Unternehmers"] G2 --> R G3 --> R R --> B["Beweislastumkehr:
Unternehmer muss Schätzung widerlegen
bei fehlenden Daten kaum möglich"] G["GitCover-Lösung"] G --> V["Vollständige GoBD-konforme Buchführung"] G --> N["Nachvollziehbarkeit (Rz. 146)"] G --> P["Nachprüfbarkeit (Rz. 147)"] G --> E["Evidence-Package (Z3+)"] V --> AV["Schätzung vermieden"] N --> AV P --> AV E --> AV style S fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style G1 fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style G2 fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style G3 fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style R fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style B fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style G fill:#10A987,stroke:#0A7F5C,color:#FBFAF7 style V fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style N fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style P fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style E fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style AV fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33

Estimation is the consequence - not the punishment: § 162 AO is not a punishment, but a consequence of unusable bookkeeping. Anyone who books GoBD-compliant (ED04-ED07) makes estimation superfluous - the auditor can read the assessment bases from the repo.

Field audit (§ 193 AO) - and how Git facilitates it

Audit type	Trigger	Frequency	GitCover support
Regular audit	Size/turnover of the company	3-5 years	Evidence package (Z3+), static web
Cause-based audit	Suspicion, hints, sample	On occasion	git bundle, `git log`, `git grep`
Follow-up	Anomalies in prior audit	After regular audit	Complete history traceable

Practical example: The auditor announces a field audit. The entrepreneur (E1) generates a Tenant Evidence Package (git bundle + static web + manifest) for the audit period. The auditor receives the USB stick, opens index.html (Z3+) or git clone (Z3), and can navigate all bookings, vouchers, procedure documentations and sidecars - offline, without IAM, without cloud account.

Voluntary disclosure (§ 371 AO) - the emergency brake

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD H["Steuerhinterziehung § 370 AO
entdeckt"] H --> SA["Selbstanzeige § 371 AO
möglich?"] SA -->|ja, wenn| V1["1. Vollständig
alle verkürzten Steuern"] SA -->|ja, wenn| V2["2. Unverzüglich
nach Entdeckung"] SA -->|ja, wenn| V3["3. Kein Prüfungsbeginn
noch keine Prüfung angekündigt"] SA -->|ja, wenn| V4["4. Nachzahlung
innerhalb angemessener Frist"] V1 --> W["Wirkung:
Straffreiheit (§ 371 Abs. 3)"] V2 --> W V3 --> W V4 --> W SA -->|nein| ST["Steuerstrafverfahren
§ 370 AO
Freiheitsstrafe bis 5 Jahre"] style H fill:#0F1B33,stroke:#0F1B33,color:#FBFAF7 style SA fill:#FDBA74,stroke:#C2410C,color:#0F1B33 style V1 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style V2 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style V3 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style V4 fill:#DBEAFE,stroke:#1D4ED8,color:#0F1B33 style W fill:#D1FAE5,stroke:#0A7F5C,color:#0F1B33 style ST fill:#FDBA74,stroke:#C2410C,color:#0F1B33

GitCover and voluntary disclosure: If an entrepreneur determines that he has evaded taxes (e.g. forgotten VAT filing), he can document the voluntary disclosure in the diary - with role: "GF", source: "E1", and a commit with justification. The completeness (§ 371 Abs. 1) is evidenced by the repo: all evaded taxes are traceable. The immediacy is documented by the uuidV7 timestamp in the diary entry.

Caution - voluntary disclosure is complex: The requirements for an effective voluntary disclosure are strict. In case of doubt always consult a tax advisor or specialist lawyer for tax law. GitCover documents the voluntary disclosure - but it does not replace legal advice.

Sanctions for AO violations

Sanction	Legal basis	Requirement	Amount
Late payment surcharge	§ 152 AO	Missed deadline for filings	up to 25,000 EUR
Estimation	§ 162 AO	Unusable bookkeeping	often to the detriment
Delay payment	§ 146 Abs. 2c AO	Outsourcing without approval	2,500-250,000 EUR
Administrative offense	§ 379 AO	Recording duty violation	up to 50,000 EUR
Tax criminal proceedings	§ 370 AO	Intentional tax evasion	Imprisonment up to 5 years
Voluntary disclosure	§ 371 AO	Freedom from punishment on completeness	- (repayment + 6% surcharge)

Risk-Leverage: Each of these sanctions is avoided or mitigated through GoBD-compliant Git use - deadline check prevents late payment surcharges, GoBD-compliant bookkeeping prevents estimation, evidence packages facilitate field audits, and the repo itself is the best evidence of orderliness.

Risk-Leverage

Today (cheap)	Tomorrow (audit-proof)	Risk mitigated
Deadline check as Git artifact	Missed deadlines avoided	Late payment surcharge § 152 AO
GoBD-compliant bookkeeping	Estimation § 162 AO avoided	Estimation to the detriment
Evidence package (Z3+)	Field audit facilitated	Delay payment § 146 Abs. 2c
`git log` as evidence	Orderliness evidenced	Administrative offense § 379 AO
Voluntary disclosure in the diary	Completeness + immediacy documented	Tax criminal proceedings § 370 AO

Harness requirement (preview)

Derivable from ED08:

ID	Requirement	Priority
FA-4.1	Deadline check file (`checks/FRISTEN_CHECK.md`)	MUST
FA-4.2	Deadline entries with date, type, tenant, voucher reference	MUST
FA-4.3	Auto-warning for deadlines under 14 days	SHOULD
FA-4.5	Resubmission marking for notices/documents	MUST
FA-6.5	10-year retention via evidence packages	MUST
FA-6.7	Static web generator for period closing (Z3+)	SHOULD
FA-12.5	Interface error logging (errors as repo event)	MUST

The complete requirement list in Harness-Anforderungen.md.

Sources

AO (§§ 78-133 - tax procedure, § 146-147 - bookkeeping/retention, § 152 - late payment surcharge, § 162 - estimation, § 169 - assessment periods, § 193-203 - field audit, § 370 - tax evasion, § 371 - voluntary disclosure, § 379 - administrative offense)
EStG (§ 41a - payroll tax filing, § 41b - payroll tax certificate)
UStG (§ 18 - VAT pre-registration)
SGB IV (§ 23 - SV contribution statement)
GoBD (BMF letter, Rz. 146 - traceability, Rz. 147 - verifiability)
AFJD/agents/ (anonymized) - SSoT concept with deadline check, field audit preparation

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 on 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.