Cybersecurity for Accounting Firms: The Importance of Choosing an Expert Partner
Accounting and consulting firms play a central role in the economy, supporting thousands of businesses every day in managing their financial and tax data. This strategic position places them at the very heart of today’s cybersecurity concerns. Cybercriminals are increasingly targeting organizations that handle large volumes of sensitive, interconnected data, making accounting firms prime targets. By 2026, cybersecurity is no longer optional for the profession: it has become a strategic imperative, as vital as regulatory compliance or the quality of services delivered.
1. A Sector Increasingly Exposed to Cyberattacks
A. Alarming Figures
Recent data confirms the mounting pressure on consulting & auditing firms. In 2024, nearly one out of two accounting firms (47% of those surveyed) suffered at least one successful cyberattack. While this is a slight decrease compared to 2020 (57%), the figure remains deeply concerning. Ransomware continues to be the most prevalent threat: according to ANSSI (France), its frequency increased by a further 15% in 2024. The most striking case was the December 2024 attack on Coaxis, which paralyzed more than 1,200 firms and indirectly impacted nearly 350,000 client businesses. This incident illustrates the scale of the damage that can occur when a central service provider is compromised.
The issue goes far beyond the accounting sector. At the national level, 62% of French businesses reported an increase in cyberattacks in 2024. Some studies suggest that six out of ten companies do not survive a major cyberattack (evidence of the devastating impact such incidents can have on business continuity).
B. Why Accounting Firms Are Prime Targets?
Accounting firms present multiple risk factors that attract cybercriminals. Their main vulnerability lies in the type of data they manage: tax information, financial records, executive and employee identities, all highly valuable assets on the dark web. Added to this is the widespread use of interconnected SaaS platforms, which, while efficient and practical, create multiple potential entry points for attackers.
The dependency chain also amplifies the risk. When one firm is paralyzed, hundreds or even thousands of client businesses are directly affected, creating a domino effect. Finally, cybersecurity culture is still insufficiently embedded in many firms. A lack of employee training on phishing attempts and risky behaviors remains a critical weakness.
2. Increasingly Stringent Regulatory Obligations
A. A Strengthened Legal Framework Since 2024
In response to these challenges, regulators have tightened requirements for the sector. Since October 2024, the European NIS2 directive has imposed stricter cybersecurity responsibilities on accounting firms. Boards of directors are now directly accountable for implementing robust protective measures: strict password policies, regular backups, automatic encryption of sensitive data, rigorous access controls, and strong authentication. The directive also requires active management of risks linked to suppliers and service providers. Non-compliance can result in fines of up to €10 million or 2% of annual global turnover.
In parallel, the Cyberscore Act, adopted in 2022, requires an annual external audit of digital systems, with results made public in the form of a cybersecurity “score.” Firms must therefore not only comply, but also demonstrate their security level to clients. The GDPR remains another cornerstone: any personal data breach may lead to fines of up to 4% of global turnover. Against this backdrop, appointing a Data Protection Officer (DPO) is no longer just advisable but is becoming the norm for larger firms. The French accounting regulator has also reinforced its requirements, emphasizing documented action plans, continuous employee training, and regular IT security monitoring.
B. Technical Standards Structuring Security
Beyond legal requirements, several international standards provide a framework for building strong security policies. ISO/IEC 27001 remains the benchmark for information security management, offering a structured approach to identifying risks, implementing controls, and auditing measures. ISA 315 (COS 315) further strengthens the reliability of automated data processing systems.
Moreover, SaaS solutions dedicated to accounting have evolved to natively integrate advanced cybersecurity features: encrypted data flows, multi-factor authentication, and next-generation firewalls. These tools enable firms to more easily comply with GDPR and NIS2 requirements while enhancing operational resilience.
3. Risks, Sanctions, and the Benefits of Compliance
A. Consequences of Non-Compliance
Failing to comply with cybersecurity obligations exposes firms to significant risks. Financially, penalties can be enormous, ranging from NIS2 fines of up to €10 million to GDPR sanctions reaching 4% of global turnover. But the consequences extend far beyond fines: a cyberattack can lead to total system paralysis, permanent loss of sensitive data, and business interruptions costing hundreds of thousands of euros.
Reputation is equally at stake. In a sector where trust underpins client relationships, a publicized cybersecurity incident can permanently tarnish a firm’s image and trigger major client losses. With NIS2, executive responsibility is now directly engaged, meaning board members may be held personally liable for cybersecurity shortcomings.
B. Compliance as a Priority and Competitive Advantage
Conversely, adopting a proactive approach to cybersecurity can become a genuine competitive edge. Firms that invest in robust systems strengthen their operational reliability: in the event of an attack, they have continuity and recovery plans that ensure business resilience. This capacity is a strong differentiator, particularly valued by clients concerned about data security.
Regulatory compliance also provides a commercial advantage. A firm certified ISO 27001, transparent about its audits, and with a positive cyberscore inspires greater trust, facilitating both client acquisition and retention. Moreover, prevention is always more cost-effective than remediation: while the average cost of a cyberattack for an SME exceeds €200,000, investments in training, audits, and system hardening typically remain far lower. Ultimately, cybersecurity enhances sector credibility and positions firms as modern, trustworthy actors aligned with best practices.
4. Case Studies of Cyberattacks on Accounting Firms
A. The Coaxis Incident
In December 2023, a cyberattack on Coaxis, a leading data-hosting provider for accounting firms, marked a turning point for the profession. The Lockbit 3.0 ransomware encrypted nearly a quarter of its systems within minutes, cutting off access to data for 1,200 firms and more than 350,000 client businesses. For weeks, a significant part of the sector was paralyzed, leading to delays in tax and social declarations, interventions by authorities (URSSAF, DGFiP), and an extensive IT reconstruction plan. Although the ransom was not paid, the financial and reputational costs were considerable, highlighting the fragility of interconnected ecosystems.
B. The In Extenso Attack
Two years earlier, in April 2021, the major accounting group In Extenso suffered a large-scale attack. Hackers encrypted all its databases and demanded a €5 million ransom, directly affecting 130,000 client files and disrupting operations across 280 offices. The group was forced to suspend all activity while organizing its response and securing its infrastructure. Beyond immediate losses, the incident accelerated awareness of cyber risks and triggered significant investments in employee training, prevention, and awareness.
5. Taking Action
A. Systelium’s Packaged Offer, Accessible to All
Partnering with Systelium provides accounting firms with a major strategic advantage in achieving compliance and protection against cyber threats. Through its externalized nearshore CISO Office model, Systelium offers French-speaking experts specialized in cybersecurity and artificial intelligence. These professionals support firms of all sizes in structuring governance, implementing technical measures, and delivering continuous employee training.
This approach not only provides access to top-level expertise that is immediately operational but also ensures cost efficiency, with rates up to 70% lower than traditional onshore firms. By relying on Systelium, accounting firms can strengthen compliance with European standards (GDPR, NIS2, ISO 27001), secure their clients’ sensitive data, and enhance credibility in a market where trust is paramount.
B. Key Takeaways
By 2026, cybersecurity has become a condition for survival for accounting and consulting firms. Rising attack volumes, increasingly strict regulatory frameworks, and the critical dependency of clients on services provided demand absolute vigilance. Legal and technical obligations are now stringent, and sanctions severe, but they also present an opportunity to turn cybersecurity into a lever of trust and competitiveness.
Firms that invest in security, compliance, and training are not only avoiding penalties: they are building a solid reputation, ensuring service continuity, and differentiating themselves in an increasingly demanding market. Cybersecurity is no longer a cost—it has become a guarantee of sustainability and a catalyst for long-term growth.