GmbH Cash Book (Kassenbuch) in Germany 2026: Requirements and Digital Solutions

For a German GmbH, the cash desk is one of the most sensitive areas of bookkeeping. Cash is anonymous, changeable at any time and therefore the classic focus of every tax audit. Those who follow the GoBD (Grundsätze zur ordnungsmäßigen Führung und Aufbewahrung von Büchern, Aufzeichnungen und Unterlagen in elektronischer Form sowie zum Datenzugriff) have little to fear. Those who ignore them risk the tax office rejecting the entire bookkeeping and estimating profit instead. This guide explains when your GmbH must keep a cash book in 2026, which requirements apply and how to meet them cleanly in digital form.

In short

• A GmbH is required to keep books as a merchant (§ 238 HGB). If it runs a cash desk with cash transactions, the Kassenbuch is mandatory.
• Cash receipts and disbursements must be recorded daily (§ 146 (1) AO) – not weekly, not at month-end.
• An Excel cash book alone is not GoBD-compliant, because it can be changed retroactively. You need an audit-proof solution with a change log.
• If the GmbH uses an electronic cash register, it has needed a certified TSE since 2020 – and must report the register to the tax office via ELSTER since 2025 (§ 146a (4) AO).
• Retention 2026: the cash book itself for 10 years, individual receipts (till slips, receipts, Z-reports) only 8 years since the BEG IV reform.
• Defects trigger income estimates (§ 162 AO) and fines up to €25,000 (§ 379 AO).

1. Does a GmbH need a cash book in 2026?

Whether a GmbH needs a cash book depends not on the legal form but on the type of transactions. As a merchant, the GmbH is fully subject to bookkeeping obligations under § 238 HGB – all transactions, including cash movements, must be recorded completely, correctly and promptly.

Important: even without a formal cash book, all cash movements must be recorded completely, correctly and promptly. Anyone claiming to run no cash desk should be able to prove it – for example through a demonstrable absence of any cash balance and an internal resolution. In practice, a properly kept cash book is almost always the safest option.

2. Legal basis 2026: HGB, AO, GoBD & KassenSichV

Cash-desk management rests on several interlocking rules:

The GoBD do not change the substance of the cash book, but strictly govern how it must be kept and stored. For a fuller overview, see the article on GoBD-compliant bookkeeping.

3. The six GoBD principles for the cash book

Every cash record must satisfy six principles. If one of them fails, the cash-desk management is formally defective:

The most critical point is immutability. Anyone who can change a posting after the fact without the change being logged does not have a GoBD-compliant cash book – no matter how neat the numbers look.

4. Mandatory fields: what belongs in every cash-book line

Each line in the cash book documents exactly one movement. A posting is complete only with these details:

1. Date of the movement (receipt date)
2. Receipt number – sequential, no gaps
3. Type: receipt or disbursement
4. Amount (gross) and, where relevant, VAT rate
5. Memo – what the money was for
6. Receipt reference – invoice, receipt, Z-report
7. New cash balance after the posting

A correct cash-book line looks like this:

The cash balance must never turn negative – a negative till is arithmetically impossible and a sure red flag for any auditor.

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5. Paper or electronic cash book?

A paper cash book is still formally permitted, but risky in practice. An Excel sheet, in turn, is not GoBD-compliant on its own: cells can be changed retroactively without creating a log – German tax courts confirmed this in 2018 and 2022.

For the GmbH, the audit-proof electronic cash desk is effectively the 2026 standard. Besides the software, a process documentation is essential: a short description of how data enters the register, who has access and how corrections are made. For how to digitise the underlying receipts cleanly, see the guide on receipt management.

6. Cash register, TSE and Z-report

If the GmbH uses an electronic cash register or a PC-based POS system, the requirement for a TSE (technical security device) under § 146a AO and the KassenSichV has applied since 2020. The TSE signs each individual cash transaction in a tamper-proof way.

Three routines follow from this:

• Every cash sale is recorded via the register with a TSE.
• A Z-report (daily close) is generated every day.
• The Z-report total must match the daily cash income in the cash book. Discrepancies (cash differences) are documented and explained.

With an open till without a technical system, a daily, counted cash report replaces the Z-report – here the burden of proof is even stricter.

7. New since 2025: reporting the register (§ 146a (4) AO)

Since 1 January 2025, electronic recording systems with a TSE must be reported to the tax office via ELSTER – under the "notification procedure pursuant to § 146a (4) AO". The serial number, TSE data and acquisition date are reported.

If your GmbH runs a TSE register and has not yet reported it, catch up immediately – the report is part of proper cash-desk management.

8. Retention periods 2026: 8 or 10 years?

The Fourth Bureaucracy Relief Act (BEG IV) shortened the retention period for accounting receipts from 10 to 8 years as of 1 January 2025. For the books themselves, the 10-year period still applies.

In concrete terms: accounting receipts from 2017 and earlier may be destroyed in 2026 – the cash book of those years may not. With an electronic register, the data must remain machine-readable in its original format.

9. Common mistakes – and what they cost

The cash desk is a perennial issue in a GmbH tax audit. These mistakes appear most often:

• Retroactive batch postings instead of daily recording
• Negative cash balance from forgotten receipts
• Z-report and cash book do not match
• Missing receipts or gaps in receipt numbering
• Excel without a change log as the sole cash book
• Unreported TSE register (§ 146a (4) AO)

The consequences are serious: formal defects entitle the tax office to an income estimate under § 162 AO – often several thousand euros. If the TSE is missing or receipts are not kept, additional fines of up to €25,000 under § 379 AO apply. In the unannounced cash inspection (§ 146b AO), the tax office checks exactly these points on site.

10. Keeping the cash book digitally – with Norman

A GoBD-compliant cash book is not created at month-end, but daily with every receipt. This is exactly where Norman comes in: receipts are captured with an unchangeable timestamp, cash and bank movements are categorised automatically and stored in an audit-proof archive. The data export for the tax office is always ready.

Because bookkeeping and invoicing are free with Norman, you get the audit-proof archive at no extra cost. For which solution otherwise suits a GmbH, see the comparison of accounting software for GmbHs.

Frequently asked questions about the GmbH cash book

Does a GmbH without cash need a cash book?

No. If the GmbH handles everything cashlessly via the bank account and runs no cash desk, no cash book is required. The absence of cash transactions should be provable, though – for example through an internal resolution and a cash balance that stays permanently at zero.

Is an Excel cash book GoBD-compliant?

Not as a standalone solution. Excel cells can be changed retroactively without creating a log – so the immutability required by the GoBD is missing. Tax courts have confirmed this. It only becomes GoBD-compliant with audit-proof software that logs every change.

How often must the cash book be kept?

Daily. § 146 (1) AO requires that cash receipts and disbursements be recorded on the day of the movement in principle. Batch postings made "all at once" at month-end contradict the GoBD and are a common audit defect.

How long must a GmbH keep the cash book?

The cash book itself for 10 years. Individual receipts such as till slips, receipts and Z-reports only 8 years – this period was shortened by the Fourth Bureaucracy Relief Act as of 1 January 2025.

Does my GmbH need a TSE?

Only with an electronic cash register or a PC-based POS system. These systems have needed a certified TSE since 2020 and must additionally be reported to the tax office via ELSTER since 2025. An open till without a technical system needs no TSE, but does need a daily, counted cash report.