ED09 - AO Basics: Taxation Procedure, Deadlines, Voluntary Disclosure

Problem

The Fiscal Code (AO) is the cornerstone of German tax law - but it is largely unknown in the SME sector:

"AO? Never heard of it." - many entrepreneurs do not know the AO, even though they work with it every day (accounting, deadlines, audits)
Missed deadlines - assessment periods, filing deadlines, limitation periods are missed because nobody 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
External audit as a bogeyman - § 193 AO (external audit) is feared, without it being clear what it means in practice
No deadline monitoring - deadlines are in the calendar, but nobody automatically warns before they expire

Core Message

The AO governs the taxation procedure - and GitCover makes the obligations arising from it machine-readable and automatically monitorable:

Deadlines as a Git artifact - checks/FRISTEN_CHECK.md with auto-warning (see ED08)
External audit as an Evidence-Package - Z3/Z3+ export (see ED05)
Avoiding estimation through GoBD compliance - complete, traceable, immutable accounting (see ED05–ED08)
Voluntary disclosure as a last resort - documented in the diary if GoBD compliance cannot be achieved

Compliance by Design: The AO obligations are not fulfilled through subsequent review, but through **structural ** Git-native compliance - deadline check, Evidence-Packages, GoBD-compliant accounting.

The Fiscal Code (AO) - Overview

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD AO["Fiscal Code (AO)"] AO --> BV["Taxation procedure
§§ 78–133"] AO --> FB["Assessment and
determination procedure
§§ 155–217"] AO --> AP["External audit
§§ 193–203"] AO --> SZ["Sanctions
§§ 152, 162, 370, 379"] BV --> AN["Filings
(LStA, UStA, SV)"] FB --> FF["Assessment periods
§ 169 AO"] AP --> Z["Data access
Z1/Z2/Z3 (§ 147 Abs. 6)"] SZ --> VS["Late-filing surcharge
§ 152 AO"] SZ --> SC["Estimation
§ 162 AO"] SZ --> ST["Criminal tax proceedings
§ 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	Provisions	SME relevance
Taxation procedure	§§ 78–133	Filings (LStA, UStA), cooperation obligations
Assessment procedure	§§ 155–217	Assessment periods (§ 169), estimation (§ 162)
External audit	§§ 193–203	Business audit, data access Z1/Z2/Z3
Sanctions	§§ 152, 162, 370, 379	Late-filing surcharge, estimation, criminal tax proceedings
Accounting	§§ 140–147	GoBD basis (see ED05–ED08)
Voluntary disclosure	§ 371	Emergency brake in the event of tax evasion

Deadlines in the Taxation Procedure

Monthly Deadlines

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Payroll tax 10. : Payroll tax filing § 41a EStG +5T : electronic +5 days section VAT 10. : VAT advance return § 18 UStG section Social security 3-last : Social security contribution statement § 23 SGB IV

Annual Deadlines

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Tax returns 31.07. : ESt / KSt / USt return ext. : Extended by tax advisor section Payroll tax certificate 28.02. : Payroll tax certificate § 41b EStG

Assessment Periods (§ 169 AO)

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% timeline section Standard case 4J : Standard period § 169 Abs. 2 Nr. 2 AO section Aggravated case 5J : For negligent reduction 10J : In the case of tax evasion

Deadline type	Deadline	Legal basis	GitCover monitoring
Payroll tax filing	10th of the following month (+5 days if electronic)	§ 41a EStG	`FRISTEN_CHECK.md` + auto-warning
VAT advance return	10th of the following month	§ 18 UStG	`FRISTEN_CHECK.md` + auto-warning
Social security contribution statement	Third-last banking day	§ 23 SGB IV	`FRISTEN_CHECK.md` + auto-warning
ESt/KSt/USt return	31.07. (extended by tax advisor)	§ 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 (shortened)	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 ED08) warns 14 days before a government deadline expires. This way, no missed deadline goes unnoticed - and § 152 AO (late-filing surcharge of 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["Estimation § 162 AO"] S --> G1["Reason 1:
Data not usable
(incomplete, altered)"] S --> G2["Reason 2:
Accounting not GoBD-compliant"] S --> G3["Reason 3:
Entrepreneur provides no information"] G1 --> R["FA estimates the tax bases
often to the entrepreneur's disadvantage"] G2 --> R G3 --> R R --> B["Reversal of the burden of proof:
Entrepreneur must rebut the estimate
almost impossible if data are missing"] G["GitCover solution"] G --> V["Complete GoBD-compliant accounting"] G --> N["Traceability (Rz. 146)"] G --> P["Verifiability (Rz. 147)"] G --> E["Evidence-Package (Z3+)"] V --> AV["Estimation avoided"] 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 penalty: § 162 AO is not a penalty, but a consequence of unusable accounting. Anyone who keeps records in a GoBD-compliant manner (ED05–ED08) makes estimation unnecessary - the auditor can read the tax bases from the repo.

External Audit (§ 193 AO) - and How Git Facilitates It

Audit type	Trigger	Frequency	GitCover support
Regular audit	Company size/revenue	Every 3–5 years	Evidence-Package (Z3+), Static-Web
Special audit	Suspicion, indications, sample	When triggered	git bundle, `git log`, `git grep`
Follow-up audit	Irregularities in preliminary review	After a regular audit	Complete history is traceable

Practical example: The auditor announces an external audit. The entrepreneur (E1) generates a Tenant Evidence Package (git bundle + Static-Web + Manifest) for the audit period. The auditor receives the USB drive, opens index.html (Z3+) or runs git clone (Z3), and can navigate all bookings, receipts, procedural documentation and sidecars - offline, without IAM, without a cloud account.

Voluntary Disclosure (§ 371 AO) - the Emergency Brake

%%{init: {'theme':'base','themeVariables':{'primaryColor':'#FBFAF7','primaryTextColor':'#0F1B33','primaryBorderColor':'#6B7280','lineColor':'#6B7280'}}}%% flowchart TD H["Tax evasion § 370 AO
discovered"] H --> SA["Voluntary disclosure § 371 AO
possible?"] SA -->|yes, if| V1["1. Complete
all evaded taxes"] SA -->|yes, if| V2["2. Without delay
after discovery"] SA -->|yes, if| V3["3. No start of audit
no audit announced yet"] SA -->|yes, if| V4["4. Repayment
within a reasonable period"] V1 --> W["Effect:
Immunity from prosecution (§ 371 Abs. 3)"] V2 --> W V3 --> W V4 --> W SA -->|no| ST["Criminal tax proceedings
§ 370 AO
Imprisonment of up to 5 years"] 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 they have evaded taxes (e.g., a forgotten VAT return), they can document the voluntary disclosure in the diary - with role: "GF", source: "E1", and a commit with a rationale. The completeness (§ 371 Abs. 1) is evidenced by the repo: all evaded taxes are traceable. The fact that it was made without delay is documented by the uuidV7 timestamp in the diary entry.

Caution - voluntary disclosure is complex: The requirements for an effective voluntary disclosure are strict. If anything is unclear, always consult a tax advisor or a specialist tax lawyer. GitCover documents the voluntary disclosure - but it does not replace legal advice.

Sanctions for AO Violations

Sanction	Legal basis	Condition	Amount
Late-filing surcharge	§ 152 AO	Missed deadline for filings	up to 25,000 EUR
Estimation	§ 162 AO	Unusable accounting	often to the entrepreneur's disadvantage
Late-payment surcharge	§ 146 Abs. 2c AO	Deferral without authorization	2,500–250,000 EUR
Administrative offence	§ 379 AO	Violation of recordkeeping obligations	up to 50,000 EUR
Criminal tax proceedings	§ 370 AO	Intentional tax evasion	Imprisonment of up to 5 years
Voluntary disclosure	§ 371 AO	No criminal liability if complete	- (repayment + 6% surcharge)

Risk leverage: Each of these sanctions is avoided or mitigated through GoBD-compliant use of Git - the deadline check prevents late-filing surcharges, GoBD-compliant accounting prevents estimation, Evidence-Packages facilitate external audits, and the repo itself is the best evidence of proper compliance.

Risk Leverage

Today (cheap)	Tomorrow (tamper-resistant)	Risk reduced
Deadline check as a Git artifact	Missed deadline avoided	Late-filing surcharge § 152 AO
GoBD-compliant accounting	Estimation § 162 AO avoided	Estimation to the entrepreneur's disadvantage
Evidence-Package (Z3+)	External audit facilitated	Late-payment surcharge § 146 Abs. 2c
`git log` as evidence	Proper compliance evidenced	Administrative offence § 379 AO
Voluntary disclosure in the diary	Completeness + promptness documented	Criminal tax proceedings § 370 AO

Harness Requirement (Preview)

Derivable from ED09:

ID	Requirement	Priority
FA-4.1	Deadline check file (`checks/FRISTEN_CHECK.md`)	MUST
FA-4.2	Deadline entries with date, type, Tenant, document reference	MUST
FA-4.3	Auto-warning for deadlines under 14 days	SHOULD
FA-4.5	Follow-up marker for notices/documents	MUST
FA-6.5	10-year retention via Evidence-Packages	MUST
FA-6.7	Static-Web generator for period close (Z3+)	SHOULD
FA-12.5	Interface error logging (error as a repo event)	MUST

The complete requirements list is in Harness-Anforderungen.md.

Sources

AO (§§ 78–133 - taxation procedure, § 146–147 - accounting/retention, § 152 - late-filing surcharge, § 162 - estimation, § 169 - assessment periods, § 193–203 - external audit, § 370 - tax evasion, § 371 - voluntary disclosure, § 379 - administrative offence)
EStG (§ 41a - payroll tax filing, § 41b - payroll tax certificate)
UStG (§ 18 - VAT advance return)
SGB IV (§ 23 - social security contribution statement)
GoBD (BMF circular, Rz. 146 - traceability, Rz. 147 - verifiability)
E1/agents/ (anonymized) - SSoT concept with deadline check, external audit preparation

Source Topology and CDN Reference Links

Role	Location	Purpose
Primary / SSoT	git.gitcover.org/GCC	Canonical repository (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 mapping 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.