Glossary

Risk-based capital

A regulatory formula for the minimum capital an insurer must hold against asset, underwriting and reserve risks, with escalating action as capital falls.

Also called: RBC, RBC ratio, NAIC risk-based capital, total adjusted capital ratio

Risk-based capital, or RBC, is the NAIC's method for testing whether an insurer holds enough capital for the risks it takes. For property and casualty insurers, the formula applies charges to asset risk, credit risk, reserve risk, premium risk and catastrophe risk, then combines them with a covariance adjustment so the risks are not simply added. Half of the combined figure is the Authorized Control Level, or ACL. The insurer's total adjusted capital, mostly statutory surplus, is divided by the ACL to give the RBC ratio.

The ratio triggers action under the NAIC's RBC model act, which states have adopted:

  • Company action level: below 200% of ACL; the insurer must file a plan with its regulator.
  • Regulatory action level: below 150%; the commissioner examines the insurer and can order corrections.
  • Authorized control level: below 100%; the commissioner may take control.
  • Mandatory control level: below 70%; the commissioner must take control.

The pitfall is reading RBC as a quality grade. It is a floor, and most insurers hold far more than the minimum. A high ratio says nothing about underwriting discipline, reserve adequacy or service. Rating agencies run their own capital models, so buyers usually look to the AM Best rating and complaint data for strength.

When an insurer fails despite the system, the guaranty fund steps in for covered claims. The guide on risk-based capital: how regulators measure insurer strength explains how regulators use the ratio, and AM Best ratings explained for business buyers covers the rating side.

Last reviewed October 10, 2026

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Related terms

Statutory surplus An insurer's admitted assets minus its liabilities under regulatory accounting rules, the capital cushion that stands behind policies beyond its loss reserves. AM Best rating AM Best's letter-grade opinion of an insurer's financial strength and ability to pay claims, widely used by lenders and contracts as a minimum standard. Guaranty fund A state-created safety net that pays covered claims, up to statutory limits, when an admitted insurer becomes insolvent. Combined ratio An insurer's claims costs plus operating expenses as a share of premium; below 100% means an underwriting profit and above 100% an underwriting loss. Written premium The total premium on policies an insurer issues or renews in a period, counted when written, whatever share of the coverage period has passed.

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