How AI Transformed the Big Four in 2025

The year 2025 marked a significant turning point for the Big Four professional services firms—Deloitte, KPMG, PwC, and EY. These industry giants moved artificial intelligence from experimental pilots to mainstream operations, affecting everything from internal workflows to client services. The firms acted as "client zero," implementing the technology within their own ranks while simultaneously guiding clients through the same transition.

Key developments included the widespread deployment of agentic AI systems, a strategic slowdown in entry-level hiring, and an aggressive pivot toward recruiting technical talent. Additionally, the commercial model of consulting is shifting, with firms exploring outcome-based pricing rather than traditional hourly billing. While these advancements promise efficiency, they also introduce new risks and challenges regarding accuracy and workforce management.

After years of investment, 2025 was the year AI tools went mainstream across audit, tax, and consulting divisions. Employees now routinely use chatbots and agentic AI systems, and clients are increasingly granted access to these platforms.

Deloitte rolled out Zora AI, an agentic platform built with Nvidia that offers clients "intelligent digital workers" capable of autonomously completing tasks. The firm also expanded generative AI features in its Omnia cloud-based audit platform and struck a deal with Anthropic to deploy Claude AI to its 470,000 employees worldwide.

EY launched its own platform, EY.ai, granting 80,000 tax staff access to 150 AI agents for tasks such as data collection and tax compliance. The firm has advanced 1,000 AI agents into development or production with plans to scale to 100,000 by 2028, investing more than $1 billion annually in AI.

PwC introduced its agent OS platform in March, deploying 25,000 intelligent agents across client operations. The firm cited partnerships with Salesforce, CrewAI, and AWS as central to its AI-led growth.

KPMG followed in June with KPMG Workbench, developed with Microsoft, connecting 50 AI agents with nearly 1,000 more in development. It also launched KPMG Velocity for advisory work and expanded its Clara audit platform.

Despite the rapid adoption, the technology is not foolproof. In October, Deloitte agreed to partially refund the Australian government after errors were discovered in a report created in part using AI.

AI's integration has accelerated a shift in focus from manpower to value, impacting hiring strategies at both the entry and senior levels. The technology is reshaping how firms approach their workforce requirements.

Entry-Level Slowdown

In August, internal documents revealed that PwC US plans to cut graduate hiring by one-third over the next three years. Leadership cited "the impact of AI" and the rapid pace of technological change as reasons for slowing associate-level hiring. The firm also noted historically low attrition rates as a contributing factor.

Senior Level Departures

AI disruption is also influencing senior partners. Many are leaving the Big Four for midsize organizations and startups, citing a faster pace, better promotion opportunities, and the chance to participate in the next wave of AI innovation.

Rise of the Technologist

While general hiring slows, demand for technical talent is surging. EY has added 61,000 technologists to its ranks since 2023, bringing their total to 15% of the workforce. PwC is "looking for hundreds and hundreds of engineers" and has created a specific engineering career path to elevate technical excellence.

Upskilling Initiatives

Firms are heavily investing in upskilling existing employees. EY rolled out an AI tool to help employees identify how their jobs will change and has awarded digital "AI badges" to nearly 100,000 employees for completing learning programs. KPMG is training interns on effective AI prompting, recognizing that strong prompting is essential for the technology's effectiveness in professional services.

The nature of the work performed by consultants and accountants is fundamentally changing. Straight advisory projects are being replaced by long-term partnerships where firms build, implement, and maintain tools for companies.

Future Workflows

According to PwC's global and US Chief Technology and Innovation Officer, Matt Wood, organizations in 2025 fit AI around existing workflows. However, the focus for 2026 will shift to "helping clients flip that model," designing processes with AI in mind from the outset.

Commercial Model Shift

EY's global managing partner for growth and innovation, Raj Sharma, indicated that the power of AI agents is forcing the firm to reconsider its commercial model. Instead of charging based on hours and resources, AI agents may call for a "service-as-a-software" approach where clients pay based on outcome.

Career Acceleration

The shift means junior work is expected to be disrupted first. At PwC, new hires are expected to be doing the roles of managers within three years, overseeing AI performing routine audit tasks. Similarly, KPMG is preparing junior consultants to become "managers of agents," managing teams of AI agents and playing a greater role in strategy decisions.