Top Audit and Actuarial Firms in 2025: Rankings and Emerging Challenges

The December 2025 issue of Best’s Review features a comprehensive special section on the top audit and actuarial firms serving the insurance industry, highlighting their critical roles, current challenges, and rankings based on loss reserves held by their insurer clients. This section underscores the importance of auditors and actuaries in ensuring the financial integrity and risk management of insurance companies, especially amid evolving regulatory and market conditions.

Roles and Importance:
Auditors provide independent opinions on the accuracy and completeness of insurers’ annual financial statements, ensuring compliance with statutory accounting principles and regulatory standards. Actuaries offer statutory actuarial opinions on policy and claim reserves, which are essential for assessing the sufficiency of reserves to cover future claims. Their expertise supports insurers in maintaining financial strength and regulatory compliance.

Ranking Methodology:
The rankings of audit and actuarial firms are based on the total loss reserves of their insurance company clients, encompassing property/casualty, life, and health insurance sectors across the U.S. and Canada. Loss reserves represent the estimated amounts insurers set aside to pay claims and related expenses. For property/casualty insurers, this includes loss and loss adjustment expense reserves; for health insurers, it includes unpaid claims and policy reserves; and for life insurers, it encompasses reserves for life and accident and health policies.

Top Firms:

• Actuarial Firms: Milliman leads with the largest life loss reserves and a significant presence in property/casualty and health sectors. Other notable actuarial firms include Lewis & Ellis, KPMG, Ernst & Young, and Willis Towers Watson. These firms serve a broad client base and handle substantial loss reserves, reflecting their influence and expertise in the industry.
• Audit Firms: PricewaterhouseCoopers (PwC) ranks highest in property/casualty loss reserves audited, followed by Deloitte, Ernst & Young, and KPMG. Johnson Lambert, EisnerAmper, and Forvis Mazars also feature prominently. These firms are recognized for their deep understanding of insurance accounting and regulatory requirements.

Emerging Challenges:
The article discusses several challenges facing auditors and actuaries in 2026, including:

• New Actuarial Guideline 55 (AG 55): Adopted by the National Association of Insurance Commissioners (NAIC), AG 55 requires enhanced transparency in asset adequacy testing for life insurance portfolios reinsured offshore. It mandates that ceding insurers disclose the results of asset adequacy testing on relevant reinsurance treaties, helping regulators assess reserve sufficiency and potential deficiencies.
• Cryptocurrency: Deregulation of cryptocurrency presents valuation and audit challenges, as these assets do not fit traditional financial definitions and carry risks such as unauthorized transactions. While insurers have been cautious, interest in cryptocurrency investments may grow, requiring auditors to adapt.
• Health Care Inflation and Cybersecurity: Rising medical costs, drug prices, and provider consolidation are driving up health insurance premiums, coupled with regulatory uncertainties affecting enrollment and risk pools. Cybersecurity remains a top priority, with auditors focusing on user access management and protection against cyberattacks, especially as workforce reductions create vulnerabilities.

Technological Impact:
Artificial intelligence (AI) is influencing actuarial and audit functions by enabling advanced predictive modeling, automated data reconciliation, anomaly detection, and continuous auditing. However, challenges remain around AI model explainability, bias, and regulatory compliance. Both actuaries and auditors will need to upskill to effectively use AI tools while applying human judgment.

Conclusion:
The Best’s Review audit and actuarial special section provides a detailed snapshot of the leading firms, their roles, and the evolving landscape of challenges they face. With regulatory changes like AG 55, technological advancements, and market pressures such as health care inflation and cybersecurity risks, auditors and actuaries are pivotal in helping insurers maintain financial strength and navigate complex risk environments.