GoBD-Compliant Charging Cost Documentation for Electric Vehicles

What Are the GoBD?

The GoBD (Grundsätze zur ordnungsmäßigen Führung und Aufbewahrung von Büchern, Aufzeichnungen und Unterlagen in elektronischer Form sowie zum Datenzugriff) are regulated in the BMF letter of November 28, 2019 (IV A 4 - S 0316/19/10003:001).

They apply to all taxpayers — regardless of company size. This affects freelancers just as much as managing directors with company cars. As soon as tax-relevant data is recorded digitally, the GoBD principles must be followed.

The 10 GoBD Principles at a Glance

The GoBD defines ten principles that every tax-relevant documentation must satisfy. Below, we explain what each principle specifically means for charging cost documentation.

1. Traceability (Nachvollziehbarkeit): Every charging session must be fully traceable from creation to tax return. This means: date, time, charging location, kWh amount, and costs must be recorded. An auditor must be able to reconstruct the complete path of a charging session — from the wallbox through the app to the DATEV export — without having to ask questions.
2. Verifiability (Nachprüfbarkeit): Closely related to traceability, but with an important distinction: verifiability requires that a knowledgeable third party can review the documentation within a reasonable time. For charging data, this means: clear labels, consistent units (kWh, EUR), and logical sorting.
3. Completeness (Vollständigkeit): All charging sessions must be documented — not just business ones. Only this way can the tax office verify the separation between private and business use. Missing entries cast doubt on the entire documentation.
4. Accuracy (Richtigkeit): The recorded data must reflect the actual facts. With wallbox integration, this means: automatic transfer of measured kWh values, instead of manual estimates. Rounded or estimated values are a common reason for objections.
5. Timeliness (Zeitgerechtheit): Charging sessions must be recorded promptly. The GoBD specifies a maximum period of 10 days. Anyone who retroactively enters all charging sessions at year-end risks having their deductions denied. The LadeKosten app records charging sessions automatically via the wallbox connection — ensuring timeliness without any manual effort.
6. Order (Ordnung): The documentation must be systematically structured — chronologically ordered and categorized by subject. A spreadsheet without clear structure does not meet the requirements. In practice, this means: charging sessions sorted by date, with clear assignment to the vehicle and charging point.
7. Immutability (Unveränderbarkeit): Once recorded, data must not be subsequently changed or deleted. Corrections must be made as new entries with reference to the original record. This principle is one of the most critical — and simultaneously the one where Excel solutions most frequently fail.
8. Individual Recording Obligation (Einzelaufzeichnungspflicht): Each charging session must be recorded as an individual business transaction. Summarized monthly or quarterly figures are not permitted. Since the elimination of the flat rate in 2026, this is precisely the new requirement: every charging session individually, with all relevant data.
9. Machine Readability (Maschinelle Auswertbarkeit): The data must be in a format that allows machine evaluation by the tax authorities — meaning no handwritten notes or photos of meter readings. The DATEV export of the LadeKosten app meets this requirement by default.
10. Data Security (Datensicherheit): Data must be protected against loss, manipulation, and unauthorized access. This includes regular backups, access controls, and secure storage. A USB stick in a desk drawer does not meet this requirement.

The Process Documentation

The GoBD requires process documentation describing how tax-relevant data is captured, processed, and archived. For charging cost documentation, this must include:

• General Description: What system is used? What data is captured?
• User Documentation: How does the user operate the software? What inputs are required?
• Technical System Documentation: How is data stored? What security measures are in place?
• Operations Documentation: How is the system maintained and updated?

This sounds complex, but is much simpler when using a specialized app: The app itself serves as the process documentation.

What Does Audit-Proof Mean?

The term 'audit-proof' (revisionssicher) is frequently used but is not a legal term. It means that a system meets the GoBD requirements for immutability. Specifically, this means:

• Data must be stored in the original format
• Every change must be logged (audit trail)
• Timestamps must be tamper-proof
• Storage must be on a permanent medium — a USB stick or local Excel file without backup is not sufficient

An audit-proof charging cost documentation prevents entries from being subsequently altered without this being detectable.

How LadeKosten Implements the GoBD Requirements

The LadeKosten app was specifically developed for GoBD-compliant documentation of charging sessions:

• Immutable Entries: Once recorded, charging sessions cannot be edited or deleted. Corrections are made as new entries with reference to the original.
• Audit Log: Every action is logged with a timestamp and can be viewed at any time.
• Automatic Recording: Via wallbox integration, kWh values are taken directly from the meter — without manual entry and thus without potential for errors.
• Local Storage: All data stays on your device. No cloud dependency, no risk from server outages.
• DATEV Export: Data can be exported directly in DATEV format — for direct import by your tax advisor.

What Happens During a Tax Audit?

Many company car users underestimate the risk of a tax audit. Yet the tax office scrutinizes charging cost documentation particularly closely when high amounts are claimed or the figures seem implausible.

What the Auditor Looks For

The tax auditor will proceed systematically, checking the following points:

• Completeness: Is there a record for every claimed charging session? Are there gaps in the chronology that suggest missing entries?
• Consistency: Do the documented kWh amounts match the vehicle's consumption? Do the charging times align with the logbook?
• Plausibility: Are the electricity costs per kWh realistic? Are the charging amounts within the physically possible range for the respective vehicle?
• Timeliness: Were all entries created promptly, or do the metadata suggest that everything was entered retroactively at year-end?
• Immutability: Is there an audit trail? Can changes be traced?

Consequences of Inadequate Documentation

If the documentation does not meet GoBD requirements, the auditor has several options:

• Estimation (Zuschätzung): The tax office estimates the actual costs — typically to the taxpayer's disadvantage. Instead of the documented EUR 3,000, for example, only EUR 500 may be recognized.
• Complete Rejection: In the worst case, all charging costs are rejected as a business expense. For a company car, this can quickly amount to several thousand euros per year.
• Interest on Back Taxes: Additional interest is charged on the tax arrears (§ 233a AO).
• Administrative Fine: In cases of particularly serious violations of record-keeping obligations, a fine of up to EUR 25,000 can be imposed (§ 146 para. 2c AO).

A tax advisor can provide support in the event of an audit — but only if the underlying documentation is sound. Without GoBD-compliant data, even the best advisor can do little.

GoBD-Compliant vs. Non-Compliant Documentation

How does GoBD-compliant documentation concretely differ from non-compliant documentation? Here is a direct comparison:

Excel Spreadsheet or Paper Notes (Not GoBD-Compliant)

• Immutability: Not given. Cells can be overwritten at any time without the change being detectable.
• Timeliness: Not verifiable. The file creation date says nothing about when individual rows were entered.
• Completeness: Not auditable. Rows can be inserted or deleted after the fact.
• Machine Readability: Limited. Custom formatting, merged cells, and inconsistent data types make evaluation difficult.
• Data Security: Not guaranteed. No automatic backups, no access controls.
• Process Documentation: Typically missing entirely.

Concrete Example: An Excel spreadsheet with columns for "Date," "kWh," and "Costs" — without timestamps, without an audit log, and without write protection — will not be accepted during a tax audit, even if the data is factually correct.

LadeKosten App (GoBD-Compliant)

• Immutability: Every entry is secured with a cryptographic timestamp. Changes are only possible as correction entries and are visible in the audit trail.
• Timeliness: Automatic recording via wallbox integration. Every entry receives a second-precise timestamp.
• Completeness: Automatic gap detection. The app warns when charging sessions are missing or implausible intervals occur.
• Machine Readability: Standardized DATEV export, which can be imported directly into common accounting software.
• Data Security: Local, encrypted storage with optional backup.
• Process Documentation: Covered by the app itself.

Concrete Example: A charging session automatically recorded on March 15 at 10:47 PM with 18.3 kWh, wallbox serial number, timestamp, and audit entry — that is documentation that withstands any tax audit.

For those who want to read the detailed comparison between Excel and LadeKosten, you will find further details about the weaknesses of manual documentation there.

Retention Periods in Detail

The retention periods for tax-relevant documents are regulated in § 147 AO. Since the Bureaucracy Relief Act IV (2025), shortened periods apply, but they are still considerable.

Which Periods Apply?

The period begins at the end of the calendar year in which the last entry was made or the document was created. A charging session recorded in March 2026 must therefore be retained until at least the end of 2034.

Digital Retention Is Mandatory

Anyone who records charging data digitally must also store it digitally. The GoBD explicitly prohibits replacing digital originals with printouts and deleting the electronic version. The original format is authoritative.

This also means: anyone who switches apps or loses their smartphone must ensure that the old data remains available and readable. The LadeKosten app offers an export in an open format that remains readable independently of the app.

What LadeKosten Offers for Long-Term Archiving

• Local Storage: All data stays on your device — no dependency on a cloud provider that could discontinue its service.
• Export in Open Formats: CSV and DATEV export enable archiving independently of the app.
• Versioned Backups: Regular backup copies protect against data loss from device changes or defects.