Accountancy practices face daily cyber threats: 2026 is the year to act

These aren’t theoretical risks - they are real incidents we are helping organisations recover from. For accountancy practices, this often involves disruption during reporting periods and exposure of sensitive financial and tax data. Cyber risk across all sectors has evolved, and the way businesses manage it now needs to evolve at the same pace.

In this article, we break down the five cyber threats firms face that cannot be ignored.

1. Advancements in social engineering techniques

In 2025, social engineering techniques became more sophisticated, more personalised, and significantly harder for staff to detect. In the context of cyber attacks, social engineering is where threat actors manipulate and deceive staff into divulging sensitive information and granting them access into systems. Rather than exploiting technical system vulnerabilities, attackers exploit human psychology, using persuasion tactics like urgency, fear, and authority to trick victims into making security mistakes.

Social engineering typically starts with the attacker researching the target using public sources like social media and company websites to create a believable scenario, often impersonating a trusted entity like IT support or a bank employee to build rapport and create a false sense of security.

Whilst phishing remains the most common entry point into an organisation, we have seen a significant rise in native-language vishing (malicious phone calls) and smishing (SMS messaging) where attackers increasingly collaborate with individuals who are culturally aligned with the target to sound credible and build trust.

For businesses entrusted with sensitive data, financial records, and client information, this presents a critical and growing risk. For accountancy firms handling payroll, tax submissions and client banking details, the impact can be immediate and severe. Protection now requires more than technology – it demands consistent staff vigilance supported by training and policies to ensure a firm is protected.

2. How AI is helping attackers breach organisations

Artificial intelligence is lowering the barrier to entry for cybercriminals, enabling attacks that exploit both technical weaknesses and human trust.

One of the most pressing risks is the exploitation of multi-factor authentication (MFA). MFA remains a critical security control, but AI has made bypassing it easier than ever. Over-reliance on MFA can create a false sense of security - highlighting the need for broader, multi-layered protection.

Credential-stuffing and brute-force attacks aren’t new, but AI and automation now allow attackers to scale and accelerate these efforts, rapidly cycling through breached credentials or targeting weaker second-factor methods like SMS codes. This dramatically increases the likelihood of unauthorised access to sensitive data and core systems.

AI has also revolutionised social engineering. Spear-phishing campaigns are now highly personalised, with AI tools analysing email traffic, writing styles, and metadata to craft convincing messages that impersonate trusted colleagues, suppliers or clients. For most businesses, this makes phishing one of the most dangerous AI-enabled threats.

Generative AI introduces a new level of risk - deepfake impersonation. Attackers can now create convincing audio, video or images of senior leaders, clients or other stakeholders, which can then be used to authorise fraudulent transactions, mislead staff or influence negotiations. In organisations and industries built on trust and credibility, that poses a significant threat.

3. Supply chain risk

Across all of our clients - including accountancy practices and other professional services firms, supply chains are emerging as one of the most significant yet least understood sources of cyber risk. Businesses are deeply reliant on core platforms, cloud services, outsourced IT providers and specialist technology vendors. When even a single supplier is compromised, the fallout can impact dozens of businesses across the supply chain simultaneously, disrupting operations and exposing sensitive data.

The recent ransomware attack on Marks and Spencer (M&S) is a clear example of how exposed organisations can be through their supply chains. While M&S was not compromised directly, a weakness within a third-party supplier created an unintended entry point, resulting in operational disruption, delays across its logistics network, significant financial losses, and a direct effect on customer services and trust. The incident reinforces a critical point: cyber resilience is only as strong as the weakest link in the chain.

UK regulators have recognised this weakness. The NCSC has made supply chain security a national priority, issuing clear principles for managing supply chain cyber risk. For organisations of all types and sizes, the message is clear: a contract and a Data Protection Impact Assessment (DPIA) are no longer enough. You must know how your providers secure their own environments, what independent assurance they can demonstrate, how they manage subcontractors, and how quickly they can contain and communicate an incident that affects your assets and data.

4. Insider threats

In our work across all sectors, we’ve found that the most serious cyber risks don’t always originate outside the organisation. An increasing number of incidents stem from individuals with legitimate access - employees, support staff, contractors, or outsourced IT providers.

Most cases are accidental: misdirected emails, documents saved in the wrong location, or information shared more widely than intended. Yet there is also a malicious element - “bad leavers” whose access was never removed, or disgruntled individuals who exploit their privileges. Once valid credentials are in play, the attacker is already inside the perimeter, and even the strongest technical controls can be sidestepped.

Managing insider risk requires more than technology. It means tightening joiner/leaver processes, enforcing privilege access, monitoring suspicious activity, and fostering a culture where mistakes are reported quickly and transparently.

5. Lack of independent assurance

A recurring issue we encounter is the misplaced belief that “our IT team has it covered.” While technical support and infrastructure management are crucial, they are not a substitute for independent cyber risk assurance. Increasingly, professional bodies and governance frameworks emphasise the importance of assurance from qualified cyber specialists - separate from your IT provider - to give boards a true picture of risks and whether controls are genuinely effective.

For organisations that hold highly sensitive data and financial assets, rely on business continuity, and where customer trust is fundamental to their business, independent assurance delivers what leadership teams need most.

It provides a clear understanding of vulnerabilities across systems, people, suppliers, and governance; outlines actionable priorities for remediation; and offers documented evidence that stands up to scrutiny from regulators, clients, and insurers.

With attacks happening daily, and with greater sophistication, merely hoping you will be secure is not a credible strategy for senior leaders.

Conclusion

The message for 2026 is simple: be proactive, not reactive.

Too many organisations come to us after a compromise - when teams are offline, confidence has been shaken, reputation is damaged, regulators must be informed, and recovery costs far exceed what preventative controls would have cost.

The alternative is infinitely better: get ahead of it. Build assurance, strengthen controls, challenge assumptions, tighten access and verify supplier resilience. Doing so will be far less disruptive, painful and costly – and will give you reassurance that your organisation and data is safe.