Premium audits are vitally important. They determine the final premium for an insurance policy, and the data collected during an audit is later submitted to rating organizations, such as NCCI and independent bureaus. This information is used in developing experience mods Workers' Compensation premiums are estimated at the start of a policy and are based on expected business operation and payroll information. To ensure these figures are accurate and classifications remain appropriate, all Workers' Compensation policies are subject to an audit to determine the actual premium. The audit takes estimated payroll and converts the policy premiums, so they are based on actual payroll. Audits are required by Workers' Compensation.