Experience Rating Mod Calculator

Actual Losses feeds only the numerator of the mod formula (through Primary Actual Losses and Excess Actual Losses), while Expected Losses -- which sets the denominator -- doesn't change. Since the denominator stays fixed, a bigger numerator always produces a bigger ratio, so Experience Mod rises whenever Actual Losses rises, regardless of how Ballast Value or the weight inputs are set.

Ballast Value is added to both the numerator and denominator of the mod formula. Because it's added equally to both sides, a larger ballast pulls the overall ratio toward 1.00 -- it dampens how far actual-versus-expected loss differences can push the final mod, which is the real formula's mechanism for preventing a single unusually good or bad year from producing an extreme rating swing.

Not exactly. This calculator applies Primary Loss Weight as a flat percentage split of total losses for simplicity. The real NCCI methodology instead splits losses per individual claim against an official primary loss threshold published for each state and policy year, so an actual experience mod worksheet won't match this tool's split exactly -- treat this as an illustration of the formula's shape, not a reproduction of the real per-claim methodology.

A mod of 1.00 means actual losses matched expected losses exactly, leaving standard premium unchanged. A mod above 1.00 means the insured's losses ran worse than expected and premium is surcharged; a mod below 1.00 means losses ran better than expected and premium is credited. Premium Impact translates that deviation into a percentage change.

No. Real NCCI experience rating derives the weighting value (often called 'W') from published credibility tables that scale with the size of Expected Losses, rather than letting the user set it directly. This calculator instead exposes Excess Loss Weight as a direct adjustable input, which makes it useful for exploring the formula's structure but means it will not reproduce a specific state's current official weighting.