Any car dealer who accepts cash – whether for vehicle sales, workshop services, or spare parts – must maintain a cash book. But what exactly does the law require? What mandatory information belongs in every entry? And how do you avoid the typical errors that can become expensive during a tax audit? This guide explains step by step how to correctly maintain your cash book and what benefits a digital solution specifically for car dealers offers.
What Is a Cash Book and Why Is It Important?
A cash book is an accounting instrument that chronologically records all cash transactions of a business. It documents every single business transaction involving cash – both income and expenses. The cash book thus forms the basis for proper bookkeeping and is a central element in tax-related profit determination.
For car dealers, the cash book has special significance: In the automotive trade, large cash sums regularly occur. Whether advance payments on used cars, cash payments for repairs, or the sale of accessories – all these transactions must be documented without gaps. Tax authorities are known to scrutinize cash management at car dealerships particularly closely.
Good to Know: The cash book should not be confused with the cash register. The register records individual sales transactions, while the cash book summarizes all cash movements of a day and chronologically integrates them into the bookkeeping.
Who Must Maintain a Cash Book? (§ 146 AO)
The obligation to maintain a cash book derives from §§ 238 ff. HGB in conjunction with § 146 AO (German Tax Code). The general rule is: Anyone required to use double-entry bookkeeping who conducts cash transactions must maintain a cash book.
Cash Book Obligation: Who Is Affected?
| Business Form | Cash Book Obligation | Remarks |
|---|---|---|
| GmbH / UG | Yes | Always subject to bookkeeping requirements |
| OHG / KG | Yes | Subject to bookkeeping as a commercial partnership |
| Sole merchant (e.K.) | Yes | Registered in the commercial register |
| Sole proprietor (not e.K.) | Yes, above threshold | Above €80,000 profit or €800,000 revenue p.a. |
| Freelancer | No | Cash basis accounting, no cash book required |
| Small business (below threshold) | No* | *Recommended if cash transactions occur |
Cash Book Obligation for Car Dealers
The vast majority of car dealers are organized as GmbH, UG, or registered merchants and are therefore strictly required to maintain a cash book. Even if you started as a sole proprietor: once you exceed the revenue or profit thresholds mentioned above, the obligation applies.
Especially in the automotive trade, where cash payments for used cars are common, proper cash management is indispensable. Since the tightening of the TSE obligation for car dealerships, tax authorities scrutinize cash documentation even more closely.
Daily Recording Obligation: What the Tax Office Expects
§ 146 para. 1 AO requires that cash receipts and cash expenditures be recorded daily. Specifically, this means:
- Every cash movement is recorded on the day of the business transaction
- At the end of each business day, the cash balance is determined
- The expected balance (per cash book) must match the actual balance (counted cash)
- Subsequent changes must remain identifiable
- Complete, chronological recording is mandatory
Practical Tip: Complete the cash count every evening – not the next morning. This avoids memory gaps and errors in the balance determination.
Cash Count Readiness: The Decisive Test
Cash count readiness refers to the ability to reconcile the book cash balance with the actual cash on hand at any time. The tax office may demand a cash count during an audit without prior notice.
Cash count readiness requires:
- Daily recording of all cash movements
- Running calculation of the cash balance
- Physical counting of the cash balance is possible
- Agreement between expected and actual balance
For car dealers, cash count readiness is particularly important: With high individual transactions (e.g. cash payment for a vehicle), discrepancies are immediately apparent. A professional POS system for car dealers ensures cash count readiness automatically.
Required Information in the Cash Book: All Fields at a Glance
For your cash book to meet legal requirements, the following mandatory information must be included in every entry:
| Field | Description | Example |
|---|---|---|
| Date | Day of the business transaction | 04/11/2026 |
| Document No. | Sequential document number | CB-2026-0147 |
| Description | Description of the transaction | Deposit on VW Golf, customer Mueller |
| Receipt | Amount for cash receipt | €2,500.00 |
| Disbursement | Amount for cash disbursement | €85.00 |
| Balance | Current cash balance after entry | €4,215.00 |
| VAT Rate | Applicable VAT rate | 19% / margin taxation |
Important for Car Dealers: When margin taxation (§ 25a UStG), commonly used in the used car trade, is applied, this must be clearly identifiable in the cash book. Use a cash book template for car dealers that already accounts for this special case.
Maintaining a Cash Book: Step-by-Step Guide
Here is how to correctly maintain your cash book as a car dealer – in seven simple steps:
Enter Opening Balance
At the beginning of each business day, enter the previous day’s cash balance as the opening balance. This must be identical to the previous day’s closing balance.
Record Receipts
Every cash receipt is individually recorded with date, document number, description, and amount. For vehicle sales, note vehicle data and customer name.
Record Disbursements
All cash disbursements – from office supplies to fuel receipts to cash vehicle purchases – are likewise individually documented.
Assign Documents
Every entry requires a supporting document. Number documents sequentially and file them chronologically – or scan them digitally.
Calculate Balance
After each entry, the new cash balance is calculated: Previous balance + receipt − disbursement = new balance.
Perform Cash Count
At the end of the day, count the cash in the register and compare the actual balance with the expected balance per the cash book.
Document Closing
Enter the closing balance and sign the daily closing. For digital cash books, this is done via electronic signature.
Common Errors in Cash Book Management – And How to Avoid Them
During tax audits in the automotive trade, auditors consistently find the same errors. Avoid these typical pitfalls:
1. Negative Cash Balance
How to avoid negative balances:
- Record private deposits before the disbursement
- Record cash receipts immediately, not just at end of day
- Enter bank withdrawals for the cash register promptly
- Regularly check the running balance
2. Missing or Incomplete Documents
Every cash book entry needs a supporting document. If the original document is missing, create a self-generated receipt with date, amount, reason, and signature. In the automotive trade, this applies especially to cash purchases of vehicles on the private market.
3. Retroactive Changes Without Identification
Corrections in the cash book are permitted but must remain traceable. In a handwritten cash book, the error is crossed out (not made illegible); in a digital cash book, a reversal entry must be made.
4. Not Maintained on a Daily Basis
Anyone who only “catches up” on their cash book at the end of the month violates the daily recording obligation. The tax office can reject the entire bookkeeping in this case.
5. Missing Individual Records
Since the tightening of cash register regulations, individual records must be kept. Lump-sum entries like “miscellaneous income” are not permissible – every transaction must be recorded separately.
Handwritten vs. Digital Cash Book
In principle, you may maintain your cash book either by hand or digitally. Both options have advantages and disadvantages:
| Criterion | Handwritten | Digital |
|---|---|---|
| Legal admissibility | Yes | Yes (with GoBD compliance) |
| Tamper resistance | High (bound book) | High (with TSE/logging) |
| Error susceptibility | High (calculation errors) | Low (automatic calculation) |
| Time required | High | Low |
| Search function | None | Full-text search possible |
| DATEV export | Manual | Automatic |
| Archiving | Physical folder (10 years) | Digital archive (audit-proof) |
Recommendation: For car dealers, a digital cash book is clearly the better choice. It saves time, reduces errors, and integrates seamlessly into the accounting software.
GoBD Requirements for the Digital Cash Book
Anyone who maintains their cash book digitally must comply with the Principles for the Proper Management and Storage of Books, Records, and Documents in Electronic Form (GoBD). These requirements have been in effect since 2015 and were last updated in 2019.
A GoBD-compliant digital cash book must meet the following criteria:
- Traceability: Every entry must be traceable from creation to the balance sheet
- Completeness: All business transactions must be recorded without gaps
- Accuracy: Entries must reflect the actual facts
- Timeliness: Recording on the day of the business transaction
- Order: Systematic and chronological filing
- Immutability: Once recorded, entries may not be altered or deleted without a trace
Immutability is the decisive criterion: Your digital cash book must have logging (audit trail) that documents every change. In combination with a TSE (Technical Security Device), tamper resistance is ensured.
Cash Book vs. Cash Report: The Difference
Many car dealers confuse the cash book with the cash report. However, these are two different documents:
| Feature | Cash Book | Cash Report |
|---|---|---|
| Method | Forward calculation | Reverse calculation (retrograde) |
| Starting point | Opening balance + receipts − disbursements | Closing balance (counted) − opening balance |
| Application | Balance sheet accounting (double-entry bookkeeping) | Cash basis accounting |
| Mandatory for car dealers | Yes (when bookkeeping is required) | Alternative for cash basis accounting |
| Individual records | Yes, each transaction individually | Daily receipts as lump sum possible |
Since most car dealerships are subject to balance sheet accounting requirements, the cash book is the right choice. The cash report is only relevant for smaller businesses using cash basis accounting.
Excel vs. Professional Cash Book Software
Many car dealers start with an Excel spreadsheet as their cash book. But at the latest during the next tax audit, it becomes clear: Excel is not a solution.
Why Excel as a Cash Book Is Problematic
- No immutability – entries can be manipulated without a trace
- No audit trail – changes are not logged
- No automatic document numbering
- High error susceptibility with manual entry
- No automatic DATEV export
- Not GoBD-compliant – tax office can reject the bookkeeping
Benefits of Professional Cash Book Software
- GoBD-compliant recording with change log
- Automatic balance calculation – negative balance impossible
- Sequential document numbering
- Integrated DATEV export for the tax advisor
- Daily closing at the push of a button
- Digital document archiving
Penalties and Consequences for Incorrect Cash Management
Incorrect or missing cash management can have severe consequences for car dealers:
- Additional assessment: The tax office estimates additional revenue, often a flat 5–10% of total revenue
- Rejection of bookkeeping: The entire bookkeeping is classified as improper
- Back-tax payments: Including interest (6% p.a.) and, where applicable, late payment surcharges
- Fines: Up to €25,000 for violations of cash management obligations (§ 379 AO)
- Criminal tax proceedings: In cases of suspected tax evasion, monetary fines or imprisonment may apply
AutoPult POS System: Maintain Your Cash Book Automatically
With the AutoPult POS system, maintaining the cash book becomes effortless. The solution, developed specifically for car dealers, automates the entire process:
- Automatic Cash Book: Every transaction is recorded in the digital cash book in real time
- GoBD Compliance: Immutable records with a complete audit trail
- TSE Integration: Certified Technical Security Device included
- Cash Count Readiness: Expected vs. actual comparison at the push of a button
- Daily Closing: Automatic cash closing with counting protocol
- DATEV Interface: Direct export to the tax advisor via DATEV
- Margin Taxation: Correct representation of § 25a UStG in the automotive trade
- Document Archiving: Digital filing of all documents – audit-proof for 10 years
Don’t want to maintain your cash book manually anymore? Download our free cash book template for car dealers or try the AutoPult POS system directly.
Frequently Asked Questions About Maintaining a Cash Book
Does every car dealer have to maintain a cash book?
Yes, provided the car dealer is subject to bookkeeping requirements (e.g. as a GmbH, UG, or e.K.) and conducts cash transactions. Sole proprietors are also required to maintain a cash book above €80,000 in profit or €800,000 in revenue per year. Since cash transactions are a regular occurrence in the automotive trade, this applies to virtually all car dealers.
Can the cash balance in the cash book become negative?
No, a negative cash balance is never permissible. Physically, a cash register cannot contain less than €0.00. A negative balance is a serious error that can lead to rejection of the bookkeeping and additional tax assessments during a tax audit.
Can I maintain my cash book in Excel?
In principle, this is possible but will not be accepted by the tax office. Excel spreadsheets are not GoBD-compliant, as entries can be changed or deleted without a trace. During a tax audit, the tax office can reject an Excel cash book. Use GoBD-compliant cash book software instead.
How long must I retain my cash book?
The cash book and all associated documents must be retained for 10 years in accordance with § 147 AO. The period begins at the end of the calendar year in which the last entry was made. For digital cash books, readability must be ensured for the entire period.
What is the difference between a cash book and a cash report?
The cash book uses forward calculation (opening balance + receipts − disbursements = closing balance) and requires individual records. The cash report uses reverse calculation (counted closing balance − opening balance = daily receipts). The cash book is mandatory for companies using balance sheet accounting; the cash report is only sufficient for cash basis accounting.
What happens during a cash register inspection?
During a cash register inspection (§ 146b AO), the tax office may check cash management without prior notice during business hours. You must immediately provide access to your cash book and enable a cash count. If the balance does not match, a full tax audit may be ordered.
What software is suitable for the cash book in a car dealership?
For car dealers, specialized software such as the AutoPult POS system is suitable, as it already integrates industry-specific requirements like margin taxation, vehicle management, and DATEV export. Generic accounting software often does not fully cover the special requirements of the automotive trade.
Conclusion: Maintaining a Cash Book Does Not Have to Be Complicated
A correctly maintained cash book protects you as a car dealer from additional assessments, fines, and back-tax payments. The key points summarized:
- Check whether you are required to maintain a cash book – as a car dealer, almost always yes
- Record all cash movements daily and individually
- Ensure complete mandatory information and gap-free documentation
- Avoid negative cash balances at all costs
- Use GoBD-compliant software instead of Excel
- Use the DATEV interface for seamless data exchange with your tax advisor
With the AutoPult POS system, you automate your cash book and meet all legal requirements – simple, secure, and developed specifically for the automotive trade.
