Accountancy Sector

Protecting the financial data your clients trust you with.

Accountancy firms handle the most sensitive financial information in their clients' lives: tax records, payroll data, company accounts, and personal financial details. This makes you an attractive target for financially motivated cyber criminals.

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The threat landscape

Financial data is the most valuable commodity on the dark web.

Accountancy practices sit at the centre of their clients' financial lives. The combination of personal tax data, corporate accounts, payroll information, and banking credentials makes accounting firms an extraordinarily valuable target for cyber criminals. Unlike a retailer breach that exposes payment card numbers, a successful attack on an accountancy firm can give attackers a complete financial picture of every individual and business you serve.

Business email compromise is the dominant threat: fraudsters compromise partner email accounts or spoof firm addresses to redirect payments, intercept tax refunds, and instruct banks on behalf of clients. Ransomware operators specifically target accountancy software and cloud-based platforms during tax season, when the pressure to restore access is at its highest. The ICO has consistently fined firms for inadequate security controls, and the reputational damage of a client notification letter is often worse than the fine itself.

Key threat areas

The risks facing your practice.

Payment Diversion Fraud

BEC actors compromise or spoof email accounts to intercept invoice payments and redirect client funds. Accountancy firms are prime targets due to the volume of financial transactions they manage.

Ransomware on Accounting Systems

Ransomware targeting accounting platforms such as Sage, QuickBooks, and Xero encrypts client data and holds it hostage at the worst possible time: year-end and tax season.

Regulatory & ICO Exposure

Inadequate security controls that lead to a breach trigger obligations under GDPR and FCA guidance, with fines, mandatory client notifications, and professional body sanctions.

Cyber risks

Threats specific to the accountancy sector.

Phishing During Tax Season

Criminals time phishing campaigns to coincide with the busiest periods, when staff are under pressure and less likely to scrutinise unexpected emails carefully.

Business Email Compromise (BEC)

Attackers compromise or convincingly spoof partner email accounts to redirect client payments, intercept bank correspondence, and impersonate the firm to third parties.

Credential Theft from Accounting Portals

Cloud-based accounting platforms are accessible from any device, making credential theft through phishing or password spraying a persistent risk.

Third-Party Software Vulnerabilities

Accounting software integrations, payroll providers, and HMRC-linked systems all represent potential entry points that are rarely subject to formal security assessment.

Weak Access Controls on Client Files

Shared drives containing client financial records often lack granular access controls, meaning a single compromised account can expose the entire client base.

Insider Data Exfiltration

Departing staff or disgruntled employees may copy client lists, financial records, or personal data. Without monitoring controls in place, these incidents are frequently missed entirely.

Unpatched Remote Access Systems

VPNs and remote desktop solutions used for hybrid working are frequent targets if not kept up to date and protected with multi-factor authentication.

Supply Chain Risk via Payroll Providers

Third-party payroll and HR providers often have privileged access to client systems. A breach at the supplier can become your breach.

FAQ

Frequently asked questions.

Why are accountancy firms targeted by cyber criminals?

Accountancy firms hold a concentration of high-value financial data: tax returns, payroll records, company accounts, and banking credentials for every client. A single breach can give attackers a complete financial profile of dozens of individuals and businesses. This makes accounting practices more valuable targets per breach than many larger organisations.

What is payment diversion fraud and how does it affect accountants?

Payment diversion fraud occurs when attackers compromise or spoof email accounts to intercept legitimate payment instructions. In accountancy, this typically involves redirecting client tax refunds, altering supplier payment details, or impersonating partners to instruct bank transfers. Social engineering testing can assess whether your team and email security controls would detect these attacks before funds are lost.

Do we need penetration testing if we use cloud-based accounting software?

Yes. While cloud providers are responsible for the security of their infrastructure, your firm is responsible for how you configure and access those platforms. Weak passwords, lack of multi-factor authentication, excessive user permissions, and insecure integrations between accounting software and other systems are all common vulnerabilities that penetration testing can identify.

How can we protect client data during tax season?

Tax season creates heightened risk because staff are under pressure, phishing volumes increase, and the volume of sensitive data in transit peaks. A combination of social engineering testing to assess staff awareness, network penetration testing to identify infrastructure weaknesses, and a review of access controls on client file systems provides practical, evidence-based protection during this critical period.