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Certified Service Providers-Certified Automated Systems Information

Public Acts 101-31 and 101-604 amended the Retailers' Occupation Tax to implement a series of structural changes to the Illinois sales tax laws to require "remote retailers" to collect and remit State and local retailers' occupation taxes. This legislation authorizes remote retailers to contract with Certified Service Providers (CSPs) to perform their tax remittance functions. Remote retailers may also use Certified Automated Systems (CASs) to calculate and remit their own taxes. 

​If you are interested in becoming a Certified Service Provider (CSP) or Certifying an Automated System (CAS) with the Illinois Department of Revenue, please request an application by sending an email to:

For more information on the CSP/CAS process, see the links below.

List of approved CSPs/CASs - (check back for updates)

NOTE: All CSPs or CASs must file electronically by participating in and using IDOR's Electronic Filing Program. For more information, visit the Electronic Filing Program for Sales & Use Tax Returns webpage.