35 ILCS 110/5
Every serviceman maintaining a place of business in this State and making sales of service involving the incidental transfer of property for use in this State (whether those sales are made within or without this State) shall, when collecting the tax as provided in Section 3-40 of this Act from the purchaser, give to the purchaser (if demanded by the purchaser) a receipt for the tax in the manner and form prescribed by the Department. The receipt shall be sufficient to relieve the purchaser from further liability for the tax to which the receipt may refer. Each serviceman shall list with the Department the names and addresses of all of his or her agents operating in this State and the location of any and all of his or her distribution or sales houses, offices, or other places of business in this State.
35 ILCS 110/5