Choosing a cash book app comes down to one question you answer before comparing a single feature: are you only keeping a cash book, or are you running an electronic till? A cash book records your cash movements, and a bookkeeping program is enough for that. An electronic till is a recording system under section 146a of the German Fiscal Code (Abgabenordnung, AO), and that requires a certified technical security module, a receipt for every transaction, and since 2025 a notification to the tax office. The German cash register regulation (Kassensicherungsverordnung, KassenSichV) explicitly excludes electronic bookkeeping programs, which is why DATEV Kassenbuch online, Lexware Office, sevDesk, WISO MeinBüro and Papierkram get by without a security module, as long as you use them to record the cash movement afterwards and do not take payment on them; a tablet till such as ready2order does need one. Once that is settled, four things decide: whether the app stores records unalterably, whether it exports into your bookkeeping, whether it works offline, and what it costs (as of September 2026). This is not tax advice.
Almost no cash moves through my own business; my case is card reconciliation. So this article stops at the point where the movement has been recorded. What happens after that, the screening and the sorting, has been handled since 19 August 2026 by Peter, my AI employee for receipts and bookkeeping. Which software suits your business overall is covered in Accounting Software for Small Businesses, and the groundwork before that in Bookkeeping Basics for the Self-Employed.
Which app fits your operation?
Decision guide for Germany, sources checked 31 October 2026. Legal form alone does not determine recording duties.
The free limit is specific: Papierkram documents one cash account per customer account in every plan; the current plan matrix governs additional features. Free does not mean unlimited or officially approved. For the device apps below, distinguish free basic access from optional purchases or a one-off price.
Function remains the legal distinction: section 1 KassenSichV distinguishes accounting programs from tills; section 146 AO governs required records. A cash payment alone does not mean every business must keep a formal cash book; see the Federal Fiscal Court decision on cash-basis accounting. Other recording duties remain. Establish your bookkeeping and transaction-recording duties before selecting software. A DATEV export helps handover; it does not certify legal suitability. This article concerns Germany.
Cash book or till: the fork in the road
For cash, section 146 (1) AO comes first: entries and records must be made individually, completely, correctly, in a timely manner and in an orderly fashion, and literally: "Cash receipts and cash payments are to be recorded daily." That applies to anyone with a cash drawer, whatever the technology. There is so far no obligation to use an electronic till at all; the open cash drawer remains permissible, unlike in Austria, where a cash register obligation applies above certain thresholds.
If you do use an electronic recording system, section 146a AO adds three duties. Who counts is defined in section 1 KassenSichV: "electronic or computer-assisted till systems or cash registers". Explicitly excluded are ticket machines and ticket printers, parking and parking permit machines as well as charging points for electric and hybrid vehicles, electronic bookkeeping programs, goods and service vending machines, ATMs, and gaming and prize machines. Subsection 2 adds EU taximeters under Annex IX of Directive 2014/32/EU and odometers, including app-based systems where the app takes over exactly that function.
That exemption is why most cash book apps need no security module. What decides it is not what a product is called but what it does: section 146a (1) sentence 1 AO applies to whoever “records transactions subject to recording, or other processes, with the help of an electronic recording system”. If the app records the cash movement afterwards, in the accounts, the exemption applies; if it records the process itself, it does not. Taking orders and payments on a tablet or phone is the clearest sign of that, but it is a sign and not the criterion: the same app can sit on either side of the fork depending on how it is used.
A second difference follows from this. Under section 146 (1) sentence 3 AO, the duty to record each transaction individually falls away on grounds of reasonableness when goods are sold for cash to a large number of unknown persons. Sentence 4 withdraws that relief as soon as an electronic recording system is in use. Buying the till means giving up the simplification.
The three duties that come with a till
Certified technical security module. Section 146a (1) AO requires every transaction subject to recording to be recorded individually, completely, correctly, in a timely and orderly manner, and protected by a certified technical security module. It consists of a security module, a storage medium and a digital interface; certification is issued by the Federal Office for Information Security (BSI). Systems without that protection may not even be advertised or placed on the market.
Receipt obligation. Under section 146a (2) AO, a receipt must be made available to the other party in immediate temporal connection with the transaction. What it must show is set out in section 6 KassenSichV: the full name and address of the supplying business, the date of issue as well as the start and end time of the transaction, the quantity and type of goods supplied or the scope and nature of the service, a unique transaction number, the consideration and the tax amount plus the applicable rate or a note on tax exemption, the serial numbers of the recording system and of the security module, and a check value with a sequential signature counter. The receipt may be issued on paper, or electronically with the recipient's consent, for example as a QR code. Where goods are sold to a large number of unknown persons, the tax office can grant relief from the receipt obligation under section 148 AO on grounds of reasonableness. For business meals this receipt matters more: if the restaurant uses an electronic till, the tax office as a rule accepts the meal as a business expense only with a TSE-secured receipt; details in Business Meal Receipts in Germany: Template.
Reporting duty. Section 146a (4) AO requires you to inform the competent tax office within one month of acquiring or decommissioning a system, by electronic transmission, naming the taxpayer, the type of systems and their serial numbers. That duty was suspended for years. Since 1 January 2025 the procedure has been available through "Mein ELSTER" or third-party software via the ERiC interface, using the form "Mitteilungsverfahren nach § 146a Absatz 4 AO". Systems acquired before 1 July 2025 had to be reported by 31 July 2025; since then the one-month rule applies from acquisition, and deregistration works the same way. Reporting is done per business premises, in a single notification covering every system there. If your practice software handles it, that can cost extra: DATEV lists the cash register notification at 10.00 euros per notification and Kassenarchiv online at 90.00 euros per till and calendar year (as of 08/2026, net).
This third point is the one people underestimate, because the till itself has long been running correctly. The notification is still a separate act, and nobody does it by accident.
Five criteria for the choice
- Unalterability. The test is section 146 (4) AO: a record may not be altered in a way that leaves the original content undetectable, or leaves it unclear whether the change was made later. A spreadsheet where you can overwrite rows does not meet that.
- Security module included or required? For a bookkeeping program: not required. For a till: mandatory, and then the question is whether it is in the price.
- Export and integration. Do the cash entries arrive as booking proposals in your accounts or as a DATEV export to your tax adviser, or does everything end up as a PDF?
- Offline use. Market stall, clubhouse, cellar. Cloud tools need a connection, device-bound apps do not.
- Price. Almost always the least important point, because the cash book sits inside a subscription you need anyway. It matters where a feature only unlocks at a higher tier.
The cash book apps compared
The second column reports what the vendors themselves say; used as a bookkeeping program, none of these apps needs a security module. No official approval stands behind any of these statements, and your cash book does not become proper through the product alone but through the whole path: setup, daily use, process documentation, export and retention.
Check the workflow before you switch: ask for a cash report, a correction preserving the original, linked receipts and an export your accountant can use. Tax-relevant club activities need separate assessment; neither “club” nor “side business” implies a blanket exemption or identical bookkeeping duties for every operation.
When it does have to be a till
If the app records the process itself, the three duties above apply and the comparison shifts. ready2order integrates the security module as a cloud TSE from its partner fiskaly, certified by the BSI on 28 May 2021, and needs no extra hardware for it. It is not part of the standard subscription, though, but a separate annual one: the vendor page lists 35.90 euros a month for the till subscription and 15.90 euros for the TSE package, plus a complete hardware bundle from 399 euros. The DSFinV-K export for an audit and a DATEV export are available, and when the internet fails an emergency mode keeps running, logging the outage in the TSE protocol and showing it on the receipts. SumUp sells its till as hardware from 249 euros with software plans from 0 euros and a Plus plan at 49 euros, with transaction fees of 1.39 percent or 0.79 percent on the Payments Plus plan, and advertises that it takes care of TSE compliance. In both cases the notification under section 146a (4) AO stays your job, not the manufacturer's.
Proposed till requirement: distinguish the bill from current law
Germany's federal cabinet approved a bill on 23 September 2026; on 6 November 2026 the Bundestag debated it at first reading and referred it to its committees, led by the finance committee (printed paper 21/8867). According to the official finance-ministry announcement, businesses with annual turnover above €100,000 would have to use electronic tills from 2028, with a proposed exemption for annual cash turnover below €12,000. Digital receipt provision would also change.
This is a legislative proposal, not an already applicable general till requirement. Checked on 7 November 2026. Choose today's software under current law and your actual usage; for longer contracts, also consider exports and a possible migration to a till system.
What comes after recording
The app gets the cash movement into the system. Then the work starts that no till function takes over: every receipt needs the right document type, every line on a statement needs its receipt, and every discrepancy needs a decision.
That is exactly where Peter starts in my business. He screens what is already recorded in the system, assigns the correct document type to each receipt, and matches the credit card statement against it line by line. He works in my real bookkeeping interface in the browser and follows a written process description; what is not in it, he does not do. I published the numbers from his first run myself: 116 receipts screened, 38 of 40 assigned correctly, a good hour. On his second run in September he had 68 receipts in the queue, checked 54 of them, and the control export afterwards showed zero discrepancies.
The two open ones matter more to me than the 38 he set. They stayed open because his process could not decide the case unambiguously, and he reported them as open instead of making them fit. With cash that matters even more than with cards: a till discrepancy is a finding you record, not a rounding error you smooth away. What AI actually delivers in bookkeeping today, and where its limit sits, is in AI Bookkeeping: What Actually Works Today, and the setup behind it in AI Agent for Bookkeeping and Inbox.
Frequently asked questions
Which cash book app is the best?
The one belonging to your bookkeeping. It stores records unalterably, produces the cash report and passes the data to your tax adviser without retyping. If your practice works with DATEV, Kassenbuch online is the obvious choice. Otherwise you start with the software you already pay for and check the five criteria against it.
Is there a free cash book app?
Yes, with limits. Papierkram includes the cash book in every plan, including the free one, though with a maximum of one till per account. Kassenwart is free and works fully offline, but claims no GoBD compliance. Das Kassenbuch for iOS costs 1.99 euros once. For a cash drawer in a real business, the export into your accounts matters more than the price (as of September 2026).
Do I need a TSE for a cash book?
No, not if you only keep a cash book. Section 1 KassenSichV explicitly excludes electronic bookkeeping programs from the definition of electronic recording systems. You need the certified technical security module under section 146a (1) AO only once the system records the process itself instead of booking the cash movement afterwards.
Do I have to report my till to the tax office?
Yes, if it is an electronic recording system. Under section 146a (4) AO you report acquisition and decommissioning within one month by electronic transmission, since 1 January 2025 through "Mein ELSTER" or the ERiC interface. Systems acquired before 1 July 2025 had to be reported by 31 July 2025. A plain cash book inside bookkeeping software is not subject to the reporting duty.
Is a cash book app approved by the tax office?
There is no official approval for individual programs. What counts is whether the records meet the requirements, above all unalterability under section 146 (4) AO and daily recording under section 146 (1) AO. “GoBD-compliant” on a product page is a vendor statement, not a certificate from the tax office.
Can I use a cash book app for a club or privately?
Privately you need no cash book in the tax sense; that is about having an overview, and a simple app on the device is enough. In a club it depends on the area: for the non-commercial side there are dedicated apps with member management and receipt numbering. Where a commercial operation within the meaning of section 14 AO sits behind it, in a club as much as in a sideline, assess the actual tax recording and bookkeeping duties; neither club status nor a sideline creates a blanket exemption.
How to take this further
Answer the fork from the first section first, in writing: does the system record the process itself, or do I record cash afterwards? Most wrong purchases start exactly here.
If you only keep a cash book, test it for a week in daily use rather than against a feature list: record the till every day, produce the cash report at the end of the week and count the cash against the balance in the cash book. If the number does not match, you will see immediately whether the app shows you the difference or papers over it. If you run a till, check three things on a quiet morning: is the security module active, can you produce the DSFinV-K export, and has the notification gone to the tax office.
Then there is the work that comes after: sorting, matching, reporting discrepancies instead of calculating them away. How I handed that part to an AI employee, with a written process description, a learning mode and a control count before and after, is what I show in my community AI Employee Framework. What an AI employee is in the first place is on the page on hiring an AI employee. What this can look like in your business is something we'll look at together.
