Statistics on the number of insured unemployed are collected as a byproduct of Unemployment Insurance (UI) programs. Workers who lose their jobs and are covered by these programs typically file claims, which serve as notice that they are beginning a period of unemployment. Claimants who qualify for benefits are counted in the insured unemployment figures. However, they only represent a portion of the total unemployed.

These data are not used to measure total unemployment because they exclude several important groups. The insured unemployed excludes unemployed workers who have exhausted their benefits; new entrants or reentrants to the labor market; disqualified workers whose unemployment is considered to have resulted from their own actions (misconduct on the job) rather than from economic conditions; and otherwise eligible unemployed persons who do not file for benefits.

In terms of employed workers, the principal groups not covered by the UI programs are self-employed workers, unpaid family workers, workers in certain non-profit organizations, and other, primarily seasonal, worker categories.