Is Workers' Compensation Covering Uninsured Medical Costs? Evidence from the 'Monday Effect'

A growing fraction of U.S. workers face a dual system of medical insurance, with generous coverage through the Workers' Compensation system for work-related injuries, but limited or non-existent coverage for off-the-job illnesses or injuries. Uninsured and under- insured workers have an economic incentive to report off-the-job injuries as work accidents. Many analysts have interpreted the high rate of Monday injuries -- especially for hard-to-detect injuries like back sprains -- as evidence of this incentive. We combine administrative data on workplace injury claims with Current Population Survey data on medical insurance coverage to compute the fraction of Monday injury claims for workers who are more and less likely to have medical insurance. We find that workers with lower medical coverage rates are no more likely to report a Monday injury than other workers.