820 ILCS 405/239
An individual shall be deemed unemployed in any week with respect to which no wages are payable to him and during which he performs no services or in any week of less than full-time work if the wages payable to him with respect to such week are less than his weekly benefit amount. The Director shall prescribe regulations applicable to unemployed individuals making such distinctions in the procedures as to total unemployment, part-total unemployment, partial unemployment of individuals, and other forms of short-time work as the Director deems necessary.
An individual's week of unemployment shall be deemed to commence only after his registration at an employment office, except as the Director may by regulation otherwise prescribe if he finds that the foregoing requirement with respect to registration would be inequitable or administratively impracticable.
820 ILCS 405/239