How is an Idaho workers' comp premium calculated?

The core formula divides your annual payroll by 100, multiplies by the classification-code base rate, then multiplies by your experience modification factor. So premium equals (payroll ÷ 100) × rate × mod. Each job classification has its own rate reflecting its injury risk.

What is a classification code base rate?

Each occupation has a class code with a base rate expressed in dollars per 100 dollars of payroll, reflecting that work's injury risk. A clerical class has a low rate while roofing or logging carries a much higher rate. Idaho rates derive from filings approved for the state.

What is the experience modification factor?

The experience mod (mod) compares your claims history to others in your class. A mod of 1.0 is average; below 1.0 lowers your premium for a strong safety record, while above 1.0 raises it after costly claims. New or small employers often start at 1.0 until they qualify for a mod.

Can I buy coverage from the Idaho State Insurance Fund?

Yes. Idaho employers can insure with the Idaho State Insurance Fund, a state-chartered carrier, or with private carriers licensed in Idaho. Qualifying large employers may self-insure with approval. This estimate reflects manual premium before carrier-specific dividends or discounts.

Does this include all my costs?

No. This is the manual premium estimate. Your final bill may include expense constants, terrorism and catastrophe loadings, schedule credits or debits, and assessments, and may be adjusted by an audit of actual payroll. Treat the figure as a planning estimate, not a quote.

Idaho Workers' Compensation Premium Calculator

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An Idaho employer’s workers’ compensation premium starts from the manual premium formula: payroll divided by 100, times the classification-code base rate, times your experience modification factor. Each job class has its own rate reflecting injury risk, and your claims history adjusts the cost up or down. This tool applies that formula to estimate your annual premium.

How it works

Rates are quoted per 100 dollars of payroll, so payroll is divided by 100 before applying the rate and your mod:

manual premium = (annual payroll ÷ 100) × class base rate × experience mod

A mod of 1.0 is average; below 1.0 rewards a strong safety record, above 1.0 reflects costlier-than-average claims. Multiple classes are summed, each with its own payroll and rate.

Example and notes

A contractor with 500,000 dollars of payroll in a class rated at 4.50 dollars per 100, with a 0.90 experience mod, has a manual premium of (500,000 ÷ 100) × 4.50 × 0.90 = 5,000 × 4.50 × 0.90 = 20,250 dollars. The same payroll in a clerical class rated at 0.30 would be only 5,000 × 0.30 × 0.90 = 1,350 dollars — showing how much the class code drives cost. Your final bill may add expense constants, loadings, and audit adjustments. Idaho employers can insure through the Idaho State Insurance Fund or private carriers; confirm your rates with your carrier.