Workers’ Compensation Premium Formula and Calculation Order
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The common starting formula is payroll ÷ 100 × the written class rate. Add every class result to get manual premium, then apply only the modifiers and charges supported by the policy or authority statement in the order shown there.
Step 1: calculate manual premium by class
For each class: payroll ÷ 100 × rate. Add the class premiums. Never apply one governing or average rate to all payroll unless the written scheme explicitly does so.
Step 2: apply the issued experience factor
An experience modifier can increase or decrease subject premium based on the applicable rating plan. Do not invent one and do not apply it when a board-provided net rate already includes the experience adjustment.
Step 3: apply schedule credit or debit
A schedule credit or debit can reflect underwriter-assessed characteristics not captured elsewhere. Availability, percentage and premium base vary, so copy the written value and sequence.
Step 4: apply the premium discount
Premium discounts can be size-graded and may apply to a defined standard-premium base. An entered percentage is only a worksheet approximation unless the policy shows that exact discount.
Step 5: enforce the minimum premium correctly
Confirm whether the expense constant is included in the minimum. Applying it twice overstates a small policy; omitting it when separately chargeable understates the total.
Step 6: add payroll charges, assessments and fees
Terrorism, catastrophe, board levies, state assessments, taxes and fixed fees can use different bases. The tool exposes its chosen base so users can compare it with written documents.
Repeat the same sequence with audited exposure
Use the Workers’ Compensation Premium & Audit Calculator to run the same ordered ledger for original and audited payroll, then isolate the true-up and paid-to-date balance.
Frequently asked questions
Is rate × payroll the final premium?
Usually not. Experience, credits/debits, discounts, minimums, assessments and fees may follow.
Why does calculation order matter?
A percentage applied before versus after another charge changes the amount, and some charges are explicitly outside experience or discount calculations.
Sources and review status
- Texas Department of Insurance — Workers’ Compensation Rate Guide
- Texas Department of Insurance — Premium Algorithm Filing
- Texas Department of Insurance — Workers’ Compensation Manual
- California Department of Insurance — Workers’ Compensation Guide
- NCCI — Application of Experience Rating
- California State Fund — Workers’ Compensation Premium Calculation Handout (2026)
- WSIB Ontario — Calculate Premium and Insurable Earnings
- WorkSafeBC — Know How Much Coverage Costs
- icare NSW — Understanding Your Premium
Sources and model boundaries were checked on 2026-10-08. CalculatorGeek Editorial Team reviewed and approved the full finance and insurance package on 2026-10-08. The cited organizations supplied source material; they did not review or endorse this CalculatorGeek package. Product terms, policy forms, laws, regulatory guidance and rates can change; current written documents and applicable authorities control.
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