Preparing for Digital Tax Audits: Preventive Accounting Checks and Analytics

10.6.2026 | ARROWS law firm

The era of paper-based audits is definitively over. Today, the Financial Administration reviews complete accounting records electronically using algorithms that can detect any discrepancies within seconds. From a business owner’s perspective, absolute digital accuracy has therefore become an essential necessity. This article will guide you in detail through the modern analytical tools used by the tax authorities and show you how to carry out a preventive audit before you submit your data to the state.

The photograph shows an expert discussing the topic of a preventive accounting audit.

Transition to electronic audits: From spot checks to large-scale data analytics
What data the authorities collect and how they work with it
Data standardisation and the European trend: What the SAF-T format will bring
Artificial intelligence and predictive models: When an algorithm sees the future
The most common software triggers of a tax audit
Responsibility for data: Why you can no longer hide behind your accountant
How a digital audit proceeds: From the notice to an additional assessment
Preventive digital audit: How to match the state’s computing power

Key takeaways

The end of the paper era: The Czech tax authorities now request the complete accounting journal in digital form and run it through their search systems.
Immediate identification of anomalies: Software automatically flags typical accounting patterns, such as extreme increases in expense invoices in December.
Cross-matching of data: Your VAT control statement is matched in real time with the filings of your business partners in the Czech Republic and abroad.
Knowledge of the industry average: The authorities use benchmarking databases. If your profitability differs significantly from the sector average, you become a target.
International sharing: Thanks to new European directives, domestic data is continuously compared with your company’s cross-border financial flows.
Preventive digital audit: A successful defence lies in the company simulating an audit using its own software before officially submitting the data.

Transition to electronic audits: From spot checks to large-scale data analytics

Traditional tax audit procedures, based on physical verification of printed documents and random sampling, had significant limitations in terms of efficiency. This lengthy administrative process has therefore been definitively replaced by a model of large-scale electronic analytics, which fully leverages automated data processing.

The fundamental prerequisite for a modern audit today is the complete handover of the accounting records to the tax administrator. The authorities require submission of the accounting journal, general ledger and accounts receivable/payable ledger in a machine-readable format. When setting internal processes and responsibilities for the accuracy of accounting data, it is often worthwhile to consult related issues of tax classification of items within tax law. This enables them to subject the full volume of the entity’s transactions to in-depth scrutiny.

The requested data then passes through central systems, where specialised algorithms carry out immediate diagnostics. Within seconds, they identify accounting anomalies or formal inconsistencies and generate a detailed risk report.

As a result, the tax proceedings themselves are highly targeted. The tax administrator does not waste time, but directs the evidentiary process exclusively to those specific items that the analytical software has already assessed as non-standard.

What data the authorities collect and how they work with it

When electronic audits are mentioned, many entrepreneurs think only of the VAT control statement. However, from the perspective of modern analytics, this is merely the proverbial tip of the iceberg. While the control statement provides the authorities with a continuous overview of transactions between VAT payers, it is far from sufficient for an in-depth corporate income tax audit.

When initiating an audit, the Czech tax office requires an export from your accounting software. If you are dealing with how to prepare exports from your ERP/accounting system so that they withstand an audit while not revealing unnecessary security risks, insights from IT and software law, cybersecurity may also help. It is interested in detailed movements on all analytic accounts. The computer then sorts your data into database tables and begins running dozens of predefined testing scripts over it, searching for illogicalities in the postings.

For example, the system examines the strict sequence of invoice numbering series (whether documents are missing or artificially inserted retroactively), matches the dates of taxable supply with the posting dates, and looks for traces of subsequent rewriting of history. The tools can immediately detect if an accounting entry dated in November was physically created in the system only in February of the following year, shortly before the return was filed.

Data standardisation and the European trend: What the SAF-T format will bring

European tax authorities have been working for years on full unification of accounting data through the Standard Audit File for Tax (SAF-T). This international standard developed by the OECD represents a universal language for the digital transfer of accounting ledgers between a company and the state.

Although the Czech Financial Administration still primarily relies on its own structure for the VAT Control Statement and specific XML exports, the introduction of SAF-T is already a current topic for international holdings. Neighbouring EU Member States are gradually and mandatorily transitioning to this unified format.

For progressive Czech companies, this means the need to adjust internal systems in time. Any analytical inconsistency or chaos in coding will be immediately exposed in raw form when exported into these unified structures, automatically alerting the authority’s system to errors.

Artificial intelligence and predictive models: When an algorithm sees the future

The Czech Financial Administration no longer relies only on static search filters, but actively deploys machine-learning models and elements of artificial intelligence. These systems are not programmed merely to look for a specific isolated error; they can analyse a taxpayer’s overall behaviour in real time.

Based on a massive amount of historical data on tax evasion, artificial intelligence creates so-called company risk profiles. The system learns to recognise subtle, at-first-glance invisible signals that typically precede tax fraud or insolvency. For example, it analyses the frequency of changes to a company’s registered office, turnover of managing directors, repeated late advance payments, or frequent filing of additional returns to reduce tax.

If, based on these dozens of minor factors, the algorithm assesses your company as risky (assigns it a high score), it will automatically include you in the tax audit plan. An investigation therefore does not have to be triggered by a single specific incorrect document, but simply because your overall economic and administrative behaviour closely resembles that of entities where fraud was actually proven in the past.

The most common software triggers of a tax audit

The Czech Financial Administration’s algorithms are not looking for accounting perfection; they primarily look for deviations. The system automatically reacts to specific behavioural patterns that in the past indicated an attempt at illegal tax optimisation. If your export shows anomalies, the system immediately classifies the entity as high-risk.

The first critical indicator is purposeful inflation of costs at the end of the tax period. The risk is a sudden increase in expenses in December, typically for consulting, marketing, or IT services. The algorithm compares average monthly costs from January to November with the last month of the year and flags unjustified fluctuations for an on-site review.

Another trigger is the absence of accruals/deferrals for long-term supplies. A common mistake is immediately posting prepaid services, rent, or annual licences around year-end directly to the costs of the current period. The Czech Financial Administration’s analytical tools search for keywords in text fields and, if the corresponding reallocation is missing, generate a request.

The authorities’ software tools also continuously calculate the trade mark-up and profit margin on goods and services sold. If, while maintaining the same supplier structure and volumes, there is a sudden and significant drop in margin, the system automatically initiates a review of transfer pricing or fictitious inflation of inputs.

High risk is also posed by invoices from entities registered at virtual addresses, without traceable staffing, or with managing directors subject to enforcement proceedings. The Czech Financial Administration carries out fully automated cross-checking of all your business partners against its internal databases of unreliable VAT payers and high-risk entities.

Identifying and eliminating these software triggers before the tax office intervenes requires experienced legal and tax oversight. ARROWS, a Prague-based law firm, will carry out a detailed analysis of your accounting data, identify risk patterns, and help you set up a watertight defence. If in doubt, contact us at office@arws.cz.

Cross-matching data across the business environment

What makes modern electronic audits an insurmountable obstacle for dishonest entities is cross-matching vast volumes of data (Big Data). Your tax profile no longer exists in a vacuum for officials. The Czech Financial Administration does not view you as an isolated entity, but as one active node in a huge network of taxpayers.

As soon as you submit your data—whether via the VAT Control Statement or during the audit itself—the system immediately looks for a mirror of your transactions in your business partners’ data. Did you claim a VAT deduction from an invoice for CZK 1 million from company XY? In a fraction of a second, the system checks whether company XY reported that identical invoice as output and duly paid the tax. If not, or if the amounts differ by even a single crown, an alarm is triggered.

In addition to direct matching, so-called industry benchmarking is also very powerful. Authorities have extensive profitability statistics across all sectors of the Czech economy. If your company shows a profit margin of 2% in an industry where the nationwide average is consistently 18%, you become an anomaly for the system.

With defending against these broad statistical comparisons, experienced tax experts from ARROWS, a Prague-based law firm (office@arws.cz) can assist you effectively, as they can justify to officials the specific cost structure of your unique business model.

Risks identified by tax authority software	How ARROWS helps (office@arws.cz)
Suspicious cost fluctuations: The system detects massive end-of-year purchases of services and requires evidence.	We will review your documentation in advance and ensure that contracts and handover protocols are watertight both formally and substantively.
Deviation in profit margins: The tax authority flags you as suspicious based on broad industry benchmarking.	We will prepare strong legal arguments and a detailed economic analysis demonstrating the specifics of your business model.
Discrepancies in cross-matching: The system shows inconsistencies involving your problematic suppliers.	We will carry out thorough contractual due diligence of your business partners and protect you against liability for unpaid tax.
International holding transactions: The software flags your payments to a foreign parent company as high-risk.	We will prepare robust transfer pricing documentation to demonstrate to the authorities the arm’s-length nature of the transactions.
Automated initiation of an audit: The tax authority downloads data and asks you to quickly explain dozens of items.	We will take over all communication with the tax authority, represent you in the proceedings, and shield your management from pressure.

International data exchange in the age of algorithms: Your company in a global network

High-income clients and owners of large companies often use cross-border structures, holding companies, or have foreign suppliers. In the past, moving money across the borders of the Czech Republic was a major complication for the local tax administrator. Today, it is simply another data source.

At the level of the European Union, comprehensive legislation on administrative cooperation in taxation (the DAC Directive) is fully implemented and integrated as of 2026. National analytical software systems are interconnected. If your Czech company sends one million euros for consulting services to its parent company in Cyprus or the Netherlands, the Czech tax authority automatically receives information from the local tax administration there on how those funds were handled.

These systems can very quickly identify aggressive tax planning. If the software assesses that payments for licences or interest flowing abroad do not comply with the arm’s-length principle (transfer pricing), or that the recipient of the payments has no economic substance in the given state (so-called substance), it will classify the transaction as high-risk. Data is shared automatically, without the official having to draft a complex international request for information.

Responsibility for data: Why you can no longer hide behind your accountant

The shift from paper to fully digital analytics is completely changing the view of responsibility for corporate accounting. In the past, if the Czech tax authority found an error, business owners often pointed the finger at an external accounting agency, arguing that it was an administrative failure by the processor.

Today, the situation is diametrically different. When the authority uses software to uncover that a company has long been distorting its margins or artificially purchasing services from fictitious companies, it is no longer an accounting typo, but systematic and deliberate management of the data flow. Legal and tax liability falls fully on the statutory body (the managing director), who is responsible for due managerial care.

The role of accountants has shifted. From mere “record-keepers” of data from paper invoices, they have become more like financial data analysts who must ensure the correct system architecture. However, the truthfulness and economic substance of the data itself must be guaranteed directly by the company’s management.

If a managing director submits an invoice to the accountant for posting for virtual services from an unvetted supplier, the authority’s algorithm will detect it and the managing director will have to prove its reality, not the accountant who merely recorded it formally.

How a digital audit proceeds: From the notice to an additional assessment

What does the initiation and course of a tax audit based on modern data analytics actually look like in practice? For a company that is not carefully prepared in advance, the entire process is significantly faster, more targeted, and much tougher.

Everything begins with an official notice to commence an audit, under which you will make your electronic accounting records available to the tax administrators in the prescribed format. From that moment, the Czech tax authority holds all the cards. The official leaves with your data and a phase of relative “silence” begins.

During this silence, only the analytical software is working. After a few weeks, the tax administrator will contact you again, but this time with a precisely targeted questionnaire. They do not want you to explain how the entire company works; instead, they will send you an exact list of fifty specific invoices in which the system has identified the risks or anomalies described above.

Your task is, for these specific items, to provide not only signed contracts and invoices, but above all tangible evidence that the performance actually took place (detailed handover protocols, email communication with the client, photos from the construction work, analytical outputs from marketing). The burden of proof lies exclusively with you. If you fail to meet it for the flagged sample, the authority will quickly assess additional tax and impose a high penalty.

Preventive digital audit: How to match the state’s computing power

When you know that you are facing the relentless computing power of the Financial Administration supported by artificial intelligence, you cannot defend yourself with just a pencil and paper. The only effective and strategic defence in 2026 is timely preparation – carrying out a preventive audit of your own data before you submit it to public authorities at all. Put simply: you must apply to your data exactly the same filter that the authority will subsequently apply.

This process is professionally referred to as an accounting data review. Your tax adviser or a specialised auditor will request a raw data export from your chief accountant, ideally even before the final tax return is prepared and filed. They will upload this file into their own licensed diagnostic software.

Your defensive software will perform the same analytical work as the authorities’ systems. It will immediately generate a clear error report for you: it will flag unmatched balances, graphically show you a suspicious spike in costs in December, and list disputed accounting transactions where the posting date illogically differs from the date of actual performance.

Thanks to this preventive check, you gain what is most valuable – time. You have the opportunity to calmly correct the identified formal errors, add missing handover/acceptance protocols to the company archive for high-risk invoices, or demonstrably post forgotten accruals/deferrals. When the tax authority actually requests your data in the future, you will provide it with a cleaned and analytically robust database that will not trigger any alarm in the officials’ algorithms.

Final summary

Electronic tax audits have completely and irreversibly changed the rules of communication between companies and the state in the Czech Republic. Physical leafing through binders has been replaced by relentless algorithms and predictive models that analyse your accounting in enormous volumes and at lightning speed. Relying on the possibility that an error will get lost in a flood of paper documents is, in today’s business environment, a path to an almost certain additional tax assessment.

Today, based on big data, official software will reliably detect purpose-made December invoices, formal inconsistencies in accruals/deferrals, as well as suspicious deviations in profit margins compared to your closest competitors. The Financial Administration links data across registers within the Czech Republic and throughout the European Union and looks for illogicalities before an official even contacts you formally.

The only reliable defence against this state data apparatus is systematic preparation and carrying out a preventive digital audit directly within your company. You must verify your accounting with a diagnostic tool before you export it to the state.

Experienced experts from ARROWS, a Prague-based law firm (office@arws.cz), will guide you safely through this demanding process and protect the value of your company against unjustified sanctions.

FAQ – Most common questions about electronic tax audits

1. Can an algorithm initiate a tax audit fully automatically without a decision by a human official?
No. Under the Czech Tax Code, the final legal decision to officially initiate a tax audit or to send a request to provide explanations is always issued by a specific person (the tax administrator). The system merely continuously generates so-called tips for review and assigns companies a risk score. It is then up to the official whether to take this data tip into account and actually send an audit to the company.

2. Where does the Financial Administration obtain data to compare margins in individual sectors?
The Financial Administration has real historical data available from millions of filed tax returns of all companies in the Czech Republic over past years. In addition, it massively combines this internal data with information from statistical offices, European commercial databases, and public information from the Collection of Deeds of the Commercial Register. The overall database is therefore enormous and statistically highly informative.

3. After an audit, must the authority provide me with a report of what exactly its software found in the data?
At the initial stage of its investigative activity, the authority will not provide you with its internal analytical reports, as they are a protected part of a non-public file. However, once it officially proceeds to taking evidence and a subsequent additional tax assessment, it must describe in the Tax Audit Report in detail, clearly and comprehensibly what exactly its findings are based on, and you have the full legal right to inspect the entire file.

4. What should I be most careful about with invoices for consulting and marketing received at the very end of the year?
This has long been the most closely monitored item by the algorithms. It is absolutely not enough for the authority to see merely a paid invoice with generic wording such as “Consulting services for December”. If you want to successfully defend such an expense in an audit, you must have real work outputs securely archived (professional presentations, prepared analyses, detailed email communication) and prove that the service brought you a real economic benefit in the relevant period and was not merely purpose-made.

5. Is it possible to subsequently and secretly adjust data in the accounting software so that the authority’s software does not detect errors?
Any purposeful and illegal manipulation or falsification of data retroactively is a criminal offence that is very easy to prove. Moreover, quality accounting programs store a so-called audit trail (system logs) in the background, which reliably shows who changed which record, exactly when, and how. A preventive audit is by no means intended for falsification, but for timely identification and lawful formal correction of inconsistencies before the authority asks an unpleasant question about them.

6. Does every minor accounting error found by the algorithm automatically mean a harsh penalty for the company?
No. Through algorithms, tax authorities primarily look for extensive systemic failures, large-scale tax evasion, and deliberate purposeful reduction of the tax base. Minor human typos, incorrectly classified items of little significance, or isolated mistakes can be easily and rationally explained during an open audit. Authorities often do not actually pursue an additional assessment or penalties in such cases if the errors do not have a material financial impact on the overall amount of tax paid.

Notice: The information contained in this article is of a general informational nature only and is intended for basic orientation in the matter under the legal framework as of 2026. Although we take the utmost care to ensure accuracy, legal regulations and their interpretation evolve over time. We are ARROWS, a Prague-based law firm, an entity registered with the Czech Bar Association (our supervisory authority), and for maximum client security we are insured for professional liability with a limit of CZK 400,000,000. To verify the current wording of regulations and their application to your specific situation, it is necessary to contact ARROWS directly (office@arws.cz). We accept no liability for any damages arising from the independent use of information from this article without prior individual legal consultation.

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