When a construction worker in Illinois is injured on the job, their weekly benefits check is not calculated based on what a supervisor thinks they earn or what is listed on a simple pay stub. The average weekly wage calculation Illinois workers’ comp law requires is specific, statutory, and — importantly — more favorable to workers than many people realize. Overtime pay, earnings from a second job, and union scale wages all factor into the number. Getting this calculation right is one of the most consequential steps in any Illinois workers’ compensation case because every wage benefit flows from it.
This article provides general legal information; consult a licensed Illinois attorney for advice specific to your situation.
The Statutory Formula: What 820 ILCS 305/10 Requires
The average weekly wage (AWW) in Illinois workers’ compensation is defined and governed by 820 ILCS 305/10. The core formula is straightforward in concept: add up all earnings during the 52 weeks immediately preceding the date of the injury, then divide by the number of weeks actually worked during that period. The result is the AWW — the foundation upon which all wage replacement benefits are built.
The statute is explicit that “earnings” includes more than base hourly wages. Tips, bonuses, commissions, overtime pay, wages from a second job, and union-scale wages are all included in the calculation. The IWCC Handbook on Workers’ Compensation, published by the Illinois Workers’ Compensation Commission, confirms that the AWW is intended to capture the full picture of what the worker actually earned — not just a simplified weekly rate — so that benefits reflect the worker’s genuine economic loss.
Why Overtime and Second-Job Earnings Are Included
This is one of the provisions that surprises many workers — and that employers and insurers sometimes fail to account for accurately. Under 820 ILCS 305/10, overtime earnings are included in the AWW calculation. For construction workers, who often work significant overtime during peak project phases or union agreements that include shift differentials and premium pay, this can meaningfully increase the AWW and, therefore, the weekly benefit amount.
The same rule applies to a second job. If an injured construction worker was also driving for a rideshare company, doing weekend contracting work, or holding any other employment position at the time of the injury, those earnings must be counted as well. The rationale is sound: workers’ compensation is meant to replace the income a worker actually loses as a result of the injury, not an artificially reduced figure that ignores part of their economic reality. Documentation is essential — keep pay stubs, W-2s, 1099s, and any records of earnings from all sources in the 52 weeks before your injury.
Weeks Worked vs. Weeks in the Year: A Key Distinction
The 820 ILCS 305/10 formula divides total earnings by weeks worked, not by 52. This distinction matters most for construction workers, whose industry is seasonal and project-dependent. A worker who earned substantial wages over 38 weeks but was laid off for the remaining 14 does not have those earnings divided by 52. The calculation uses only weeks in which the worker actually performed work and received earnings.
This protects workers from having their AWW suppressed by unpaid periods outside their control, ensuring benefits reflect actual earning capacity rather than a diluted annual average.
From AWW to TTD: How Benefits Are Calculated
Once the AWW is established, the weekly benefit amount for temporary total disability (TTD) — the benefit paid when an injury prevents all work — is calculated as two-thirds of the AWW. TTD benefits are subject to a statewide maximum that is updated annually by the IWCC. Injured workers and their attorneys should always verify the current maximum benefit rate directly from the IWCC benefit rate tables published at iwcc.illinois.gov, as these figures change from year to year and any specific dollar amount in an article or online resource may quickly become outdated.
What does not change is the two-thirds formula itself, which is established by statute. A worker with a higher AWW — reflecting overtime, second-job earnings, and union wages — will receive a correspondingly higher weekly TTD benefit, up to the current state maximum. Workers at the lower end of the wage scale will receive two-thirds of their actual AWW, which is designed to reflect their real economic loss without creating an incentive to remain out of work.
Common Errors in AWW Calculation — and How to Catch Them
AWW disputes are among the most frequent issues in Illinois workers’ compensation claims. Employers and their insurance carriers sometimes calculate the AWW using only base wages, leaving out overtime and union-scale premium pay. They may use 52 as the divisor even when the worker had significant unpaid periods, resulting in a lower AWW. They may exclude earnings from a second employer entirely.
Workers pursuing an Illinois construction workers’ compensation claim should request a copy of the AWW calculation from the insurer and compare it against their own earnings records. If the numbers do not match — or if overtime, premium pay, or second-job income is missing from the calculation — that discrepancy should be raised with an attorney immediately. An incorrectly low AWW will understate every benefit paid throughout the life of the claim, including TTD, temporary partial disability (TPD), and permanent partial disability (PPD) awards.
Union Workers: Scale Wages and the AWW
For union construction workers in Illinois, the AWW calculation can involve additional considerations. Under 820 ILCS 305/10, union scale wages — the contractually established rate of pay — are part of the earnings picture. If a union worker was paid at a particular scale rate and received fringe benefits, shift differentials, or other negotiated compensation, all of these elements factor into the AWW. Union members should make sure their attorney has access to the applicable collective bargaining agreement and payroll records to ensure the AWW calculation reflects the full scope of their union compensation package.
The IWCC benefit rate tables published annually at iwcc.illinois.gov provide the current maximum weekly benefit rates and the corresponding AWW thresholds. Consulting those tables — and having an attorney review the calculation against your actual earnings records — is the most reliable way to confirm that your benefits are being paid accurately from the start of your claim.
Talk to a Chicago Attorney — Free Consultation
If you or a family member has been affected, the attorneys at Phillips Law Offices are here to help. Call (312) 346-4262 or contact us online for a free, no-obligation consultation.