35 ILCS 110/10
Where property is acquired as an incident to the purchase of a service from a serviceman for use in this State by a purchaser who did not pay the tax herein imposed to the serviceman, and who does not file returns with the Department as a serviceman under Section 9 of this Act, such purchaser (by the last day of the month following the calendar month in which such purchaser makes any payment upon the selling price of such property) shall, except as hereinafter provided in this Section, file a return with the Department and pay the tax upon that portion of the selling price so paid by the purchaser during the preceding calendar month. Such return shall be filed on a form prescribed by the Department and shall contain such information as the Department may reasonably require.
When a purchaser pays a tax herein imposed directly to the Department, the Department (upon request therefor from such purchaser) shall issue an appropriate receipt to such purchaser showing that he has paid such tax to the Department. Such receipt shall be sufficient to relieve the purchaser from further liability from the tax to which such receipt may refer.
A user who is liable to pay Service Use Tax directly to the Department only occasionally and not on a frequently recurring basis, and who is not required to file returns within the Department as a serviceman under Section 9 of this Act, or as a serviceman under the "Service Occupation Tax Act", or as a retailer or user under the "Use Tax Act", or as a retailer under the "Retailers' Occupation Tax Act", need not register with the Department. However, if such a user has a frequently recurring direct Service Use Tax liability to pay to the Department, such user shall be required to register with the Department on forms prescribed by the Department and to obtain and display a certificate of registration from the Department. In that event, all of the provisions of Section 9 of this Act concerning the filing of regular monthly, quarterly or annual tax returns and all of the provisions of Section 2a of the "Retailers' Occupation Tax Act" concerning the requirements for registrants to post bond or other security with the Department, as the provisions of such sections now exist or may hereafter be amended, shall apply to such users to the same extent as if such provisions were included herein.
35 ILCS 110/10