There are two reasons for the nationwide prevalence of the base period Illinois uses. First, a base period of the first four of the last five quarters generally ensures that unemployment insurance will be available for workers with a genuine attachment to the labor force, but not necessarily for those with only a marginal connection. The legislative history of the Social Security Act indicates that unemployment insurance was intended to be limited to individuals with established ties to the workforce. The Ways and Means Committee's report on the Social Security Act noted the program was not intended to provide relief for everyone who was out of work. Congress' intent still makes sense today.
Unemployment insurance is funded almost exclusively by employers.
In Illinois, it is funded 100 percent by employers. Employers alone should not bear the burden for individuals with little or no attachment to the world of work. Second, a base period like Illinois' streamlines administration and minimizes the risk of fraud. Within a month following the close of each quarter, Illinois employers provide the state with reports on the wages paid to their workers during that quarter. The state uses those reports to verify that claimants are monetarily eligible for unemployment insurance.