To find out if you qualify, write a letter of request to the Illinois Department of Revenue, Sales. Use Gusto's salary paycheck calculator to determine withholdings and calculate take-home pay for your salaried employees in Illinois.Download and complete Divorce, Child Support, and Maintenance forms from the Illinois Office of the Courts. This document is sometimes referred to as the charter. It is often described as the law that keeps citizens in the know about their government. Annually, match the taxes withheld from employees, and pay both the employee's and employer's FICA and Medicare taxes at the proper time. Can a company created or registered in a U.S. territory be considered a reporting company?