Tax season is over in the U.S, and many U.S.-based organizations may feel they’re past the peak of tax-season cyber risk. But for businesses operating in or with Canada, tax season isn’t over just yet—the filing deadline extends through April 30. And for cybercriminals, that overlap creates the perfect opportunity.
While most security awareness efforts focus on the lead-up to tax deadlines, attackers frequently start shifting tactics after filing season ends, targeting finance teams when vigilance starts to drop. The result? A surge in fraud, phishing, and business email compromise (BEC) attacks that can be just as damaging—if not more so—than pre-deadline threats.
This blog will dive into this post-tax season threat surge and how organizations can bolster their cybersecurity defenses in anticipation.
During tax season, finance and accounting teams are usually on high alert. They are used to scrutinizing emails, verifying requests, and following stricter processes because of the sheer amount of phishing scams that take place during this time. But once deadlines pass, that intensity naturally declines.
However, the smarter cyber attackers will take advantage of this window, knowing that employees are less suspicious of “late” or “follow-up” requests, processes typically become less rigid after tax season, and security teams have other areas to shift focus to.
Cybercriminals often wait until after filing deadlines to launch more convincing attacks like:
After tax season, many of these messages feel plausible because they align with real post-filing scenarios.
Additionally, tax season and post-tax season are busy times for finance teams. They spend this time reconciling accounts, processing payments, tax returns and refunds, and communicating with vendors and tax authorities.
This level of increased financial activity creates the perfect environment for fraudulent payment requests and invoice manipulation schemes to slip through unnoticed.
Another one of the most dangerous post-tax-season threats is business email compromise (BEC). BEC is when attackers impersonate someone in your organization; for example, your CFO or finance executives, partner vendors or tax consultants, or even payroll and HR personnel. They use tactics like urgent wire transfer requests, changes to vendor banking information or requests for sensitive financial documents.
Because these attacks rely on social engineering rather than malware, they often bypass traditional security tools.
Here is the good news: ahead of tax season ending, there are some practical steps organizations can take right now to reduce risk.
First, businesses should reinforce email security controls. This means enabling advanced phishing protection and impersonation detection; implementing DMARC, DKIM, and SPF properly; and flagging any external emails clearly so that users know if something came from outside the organization.
Read more in our blog: Email Security: What Every SMB Needs to Know to Stay Protected
Next, have strongly enforced IAM policies. Multi-factor authentication must be required across all systems internally, but especially anything finance-related. Least-privilege access controls should also be applied across the entire organization. Lastly, all suspicious login behaviours must be flagged and monitored (such as impossible travel, unusual devices, etc.)
Similarly, implement payment verification protocols for all types of payments. For example, require phone call verification for things like wire transfers or banking detail changes. There should be established dual approval workflows for high-value transactions.
Additionally, organizations should increase security awareness. Don’t let training stop after tax season ends. A good security awareness training program should send targeted reminders about post-tax scams, share real-world examples of recent attacks and run phishing simulations focused on finance teams.
Lastly, monitor for anomalous activity. This means watching for anything unusual regarding financial transactions, vendor record changes or other suspicious behaviours. Organizations can employ the help of a SIEM or managed detection and response teams to analyze and correlate suspicious behaviour.
Tax season may be coming to a close, but the threat landscape doesn’t follow a calendar.
Organizations that relax their defenses after Tax Day may find themselves exposed at precisely the wrong moment—when attackers are actively exploiting the post-deadline lull.
For MSPs and IT leaders, now is the time to double down on protections, reinforce best practices, and ensure finance teams remain a hardened line of defense—not an easy target.
