Reference
4 rating agencies
Financial strength & credit
Carrier Ratings, decoded.
When a certificate of insurance shows "A.M. Best A- (Excellent) VIII," a quote letter notes "S&P AA-," or a reinsurance treaty references a rating downgrade trigger — this is what those codes mean. Four agencies dominate the rating of insurance carriers, each with its own scale and emphasis. Knowing how to read them is part of the basic underwriting and broker toolkit.
AM Best — the insurance specialist
AM Best is the rating agency built specifically for the insurance industry. Its ratings are the most widely used in commercial insurance for evaluating insurer financial strength, and AM Best ratings appear on essentially every reinsurance treaty, broker quote, and risk-management acceptance document. Two components: a Financial Strength Rating (FSR) measures the insurer's ability to meet ongoing obligations to policyholders, and a Financial Size Category (FSC) measures the insurer's adjusted policyholders' surplus in fifteen tiers.
AM Best Financial Strength Ratings
A++ / A+
Superior
Carriers with the strongest ability to meet ongoing insurance obligations. The bar for many reinsurance treaty securities and most large-account broker placements.
A / A-
Excellent
The working minimum for most US admitted commercial business. Many corporate risk-management policies require "A- or better" on all participating carriers.
B++ / B+
Good
Adequate financial strength. Acceptable for many smaller commercial accounts but often disqualified by larger buyers' insurance specifications.
B / B-
Fair
Below the threshold of most corporate insurance specifications. Common in E&S start-ups and specialty programs but typically requires explicit buyer acceptance.
C++ / C+
Marginal
Marginal ability to meet ongoing obligations. Largely unacceptable for commercial placement outside very specific specialty contexts.
C / C-
Weak
Weak ability to meet obligations. Rarely seen on active commercial business.
D
Poor
Poor financial condition. Active business with D-rated carriers is typically a red flag.
E
Under regulatory supervision
Carrier is under formal regulatory supervision. New business halted; existing business in run-off.
F
In liquidation
Carrier is in formal liquidation. Claims paid by state guaranty funds within statutory limits.
S
Rating suspended
Rating temporarily suspended pending information or material event. Often appears during M&A or major restructurings.
NR
Not rated
Carrier has not requested or received a rating. Common for very small mutuals, captives, and offshore reinsurers.
AM Best Financial Size Categories
FSC XV
$2B+ surplus
Largest commercial carriers. Major reinsurance treaty securities typically require FSC IX or higher.
FSC IX–XIV
$250M – $2B surplus
Mid-to-large commercial carriers. Standard threshold for most large commercial accounts.
FSC IV–VIII
$25M – $250M surplus
Regional carriers and specialty writers. Common in E&S and program markets.
FSC I–III
Under $25M surplus
Small carriers, niche writers, captives. Typically requires explicit acceptance on commercial placements.
S&P Global Ratings — the credit agency
Standard & Poor's rates insurance carrier financial strength on its credit scale (AAA through D). S&P ratings dominate reinsurance and capital markets contexts. The scale is universally recognized by investors, regulators, and reinsurance buyers, even when AM Best is preferred for primary insurance placement decisions.
AAA
Extremely strong
Reserved for the very strongest carriers. Almost no commercial primary carriers hold AAA; some large reinsurers and Lloyd's ratings approach this level.
AA+ / AA / AA-
Very strong
Very strong financial security. Most major commercial reinsurers operate in this range.
A+ / A / A-
Strong
Strong financial security. Most major US admitted commercial carriers fall in this range. Roughly equivalent to AM Best A- to A+.
BBB+ / BBB / BBB-
Adequate
Adequate financial security. The investment-grade floor. Below BBB- is typically called "junk" or speculative grade.
BB+ to BB-
Marginal
Marginal financial security. Speculative-grade. Most corporate insurance specifications exclude carriers below investment grade.
B and below
Weak to default
Weak financial security descending to default. Active business at these levels is exceptional.
Moody's and Fitch — the other two majors
Moody's Investors Service rates insurance financial strength on the Aaa/Aa/A/Baa/Ba/B/Caa/Ca/C scale. Fitch Ratings uses an AAA/AA/A/BBB/BB/B/CCC/CC/C/D scale similar to S&P. Both agencies are widely used in reinsurance and capital markets but appear less often on US primary commercial certificates. The three credit-agency scales (S&P, Moody's, Fitch) translate cleanly between each other; AM Best's scale is conceptually similar but the codes do not map one-to-one.
Demotech — the regional and specialty agency
Demotech rates US property & casualty carriers, with particular emphasis on regional specialty writers — Florida homeowners, specialty workers compensation, niche commercial. Demotech's Financial Stability Rating ("A" Exceptional through "S" Substantial) is widely accepted by Fannie Mae, Freddie Mac, and state regulators as an alternative to AM Best for smaller carriers. Most large commercial accounts still default to AM Best, but Demotech is the dominant rating for many regional admitted lines.
How underwriters use ratings
Acceptance
Minimum carrier rating
Most corporate insurance specifications set a minimum carrier rating ("A- VIII or better" is the canonical standard). Any participating carrier below this rating triggers approval workflows or disqualification.
Reinsurance
Treaty security ratings
Most reinsurance treaties contain rating-trigger clauses that allow the cedent to terminate or collateralize if a reinsurer is downgraded below a threshold (often A- or BBB+).
Lender
Real estate & finance covenants
Commercial mortgage and construction lender covenants specify minimum carrier ratings on property insurance, often A- VIII or better. Failure to comply can trigger default.
Captive
Fronting carrier requirements
Captives that need admitted paper rely on fronting carriers, whose ratings (typically A- to A) the captive then borrows on certificates. Captive structures often hinge on fronting carrier rating stability.