35 ILCS 115/5
Every supplier maintaining a place of business in this State and making sales of tangible personal property for the purpose of resale as an incident to the sales of service taxable under this Act (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 serviceman, give to the serviceman (if demanded by the serviceman) a receipt for the tax in the manner and form prescribed by the Department. The receipt shall be sufficient to relieve the serviceman from further liability for the tax to which the receipt may refer. Each supplier 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 115/5