Tax Season is Open Season: How Accounting Firms Can Strengthen Their Cyber Defenses

Introduction

Take a second to picture this.

It’s early 2026. The holidays have ended, your firm has just wrapped a record-breaking year and your team is ready to tackle tax season head-on, with force. Then, without warning, a message flashes across your screen. It’s your IT department: “We’ve detected suspicious activity involving client data.”

In an instant, everything changes. The clients you’ve served for years, the ones who trust you with their most sensitive data, may now have their information exposed. You’re left to make the call explaining that their data could be at risk.  

This isn’t a distant scenario, it’s a growing reality. Accounting firms are increasingly in the crosshairs of cybercriminals and tax season is their busiest hunting ground. According to Accounting Today, accounting firms have seen a 300% increase in cyber attacks. With more client data moving through digital systems than any other time of year, even a single weak link can expose firms to ransomware, data theft, and reputational damage.

This blog explores why cyberattacks on accounting firms spike during tax season, what makes CPA data especially valuable, and the practical steps firms can take to protect their clients, staff, and operations while building a future-ready digital foundation.

Why Do Cyberattacks Increase for Accounting Firms During Tax Season?

Cyberattacks on CPA firms surge during tax season because threat actors exploit pressure, volume, and access. When workloads are high and deadlines tight, vigilance drops creating ideal conditions for phishing, ransomware, and data theft.

And while remote work has added a new layer of complexity, it’s provided another access point for cybercriminals. With more employees, contractors, and seasonal interns accessing firm systems from home or client sites, each device and network connection can represent a potential entry point for cybercriminals.

According to CPA Practice Advisor, 15% of U.S. accounting firms reported they had experienced a breach, despite 99% saying online security was important. This gap underscores the growing challenge in the profession: awareness doesn’t translate into preparedness.

What Makes Accounting Data So Attractive to Cybercriminals?

Most firms know the value of their data, but few realize just how lucrative it is to attackers. Accounting data combines financial, personal, and business information that can be sold, ransomed, or exploited. Unlike single-use credit card data, CPA firm databases include enduring client records: Social Security numbers, payroll files, and confidential financial statements.

3 Factors That Elevate Risk for CPA Firms

1. High Data Density: Even small firms handle hundreds of clients, each with multiple sensitive data points.
2. Seasonal Volume Spikes: Temporary staff, client uploads, and remote logins multiply exposure points.
3. Inconsistent or Under-Maintained Systems: Some firms continue to operate in environments that may not have the latest security patches or access controls, leaving potential openings for attackers.

Third-party risks are also rising. Many CPA firms rely on outside vendors for IT, payroll, or document storage. If those providers don’t maintain strong cybersecurity practices, they can inadvertently become the entry point for an attack. Conducting due diligence and ensuring vendors comply with your firm’s data-protection standards is now essential.

For firms, the question isn’t whether the data is valuable—it’s how to keep it secure while maintaining the efficiency and client experience today’s market demands. Strengthening access controls, securing document exchange, and vetting third-party connections are now table stakes for protecting both client trust and firm reputation.

How Can CPA Firms Strengthen Data Security Before Tax Season

Proactive cybersecurity has been a consistent, critical business imperative since the dawning of the dot.com era. Strengthening defenses before tax season reduces disruption, protects reputation, and ensures compliance with evolving regulations.

1. Update Core Systems and Software
   Just like your smartphone needs regular updates to patch security vulnerabilities, your firm’s software requires the same care and attention. Regular updates close gaps that cybercriminals exploit, reinforce protection against emerging threats, and help ensure your systems stay compliant with the latest data security standards.
2. Enforce Role-Based or Field-Level Security
   Limit who can access sensitive client data. Implement granular permissions so only authorized staff can view, edit, or transmit confidential files. This reduces insider risk and supports audit readiness.
3. Enable Multi-Factor Authentication (MFA)
   Adding a second verification step (e.g., mobile code or security key) can block 99% of account compromise attempts. Make MFA mandatory across client portals, payroll tools, and document management systems.
4. Encrypt and Monitor Data End-to-End
   Ensure all client files — whether in transit or at rest — are encrypted. Use centralized monitoring tools that flag suspicious downloads, logins, or unusual file movement.
5. Educate Staff and Clients
   People remain the weakest link. Conduct phishing simulations, provide short training refreshers, and communicate safe file-sharing practices to clients, especially during busy season.

Why Security is the Foundation of the Future-Ready Firm

Firms that view security as a business enabler — not just a safeguard — are better positioned for long-term growth.

A future-ready firm builds trust through transparency, resilience, and proactive governance.

• Secure systems protect client relationships and brand reputation.
• Automation and integrated platforms reduce manual errors and access risk.
• Strong compliance postures open doors to larger, more complex engagements.

As technology and regulation evolve, the most successful accounting firms will be those that balance efficiency with vigilance — ensuring innovation never outpaces protection.

Conclusion

Cybersecurity has become one of the most defining priorities for accounting firms, especially during tax season.

Building a secure foundation isn’t just about preventing breaches; it’s about ensuring continuity, compliance, and client confidence for the long term.

For more practical ways to protect sensitive client information

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