Calculate Sales Tax

• 1). Calculate the total cost of the items the customer purchased on your website.
  
  
• 2). Multiply the total amount by 6.25, the Illinois online sales tax percentage.
  
  
• 3). Record this figure. This is the online sales tax due to the state of Illinois for the purchases the Illinois customer made online. You may remit this payment through the website for Illinois Revenue, via phone or by mail.
  
  

Calculate Use Tax

• 1). Check the receipt of items you purchased online to find out whether the retailer charged the Illinois use tax. Write down the cost of the items for which you did not pay the use tax and calculate the total cost. Include the cost of all such purchases made in the previous year if you are preparing a tax return.
  
  
• 2). Multiply the total amount by 6.25, the Illinois online sales tax percentage. Use a calculator or perform the calculation with pen and paper.
  
  
• 3). Write down the figure. This amount is the use tax due to the state of Illinois for the purchases you made online. You may file Form ST-44, Illinois Use Tax Return, online and make the payment with a credit card or electronic transfer from your savings or checking account. You may make the payment by April 15 if the tax on purchases is less than $600, or pay it on the last day of the month following the month of purchase if it is $600 or greater.