Based on changes to Illinois state tax law, Amazon will begin calculating, collecting, and remitting retailer occupation tax for all orders shipped to customers in Illinois on January 1, 2021.
Your existing tax calculation and account settings do not require any changes as a result of the legislation. Order details and payment reports will automatically reflect any tax Amazon collects and remits from your orders.
The Illinois Department of Revenue published a resource page "Leveling the Playing Field for Illinois Retail Act" and flow chart for your reference. However, you may consider working with your tax advisor to determine if your business has any other ongoing tax remittance or reporting obligations.
Answers to common questions are available in the Marketplace Tax Collection FAQ.