Illinois Department of Revenue

Avoid Common Filing Mistakes for Sales and Other Related Taxes


Filing electronically is the best way to avoid common, and sometimes costly, mistakes. Most sales and other related tax forms can be filed for free using MyTax Illinois. Once you submit your return electronically, do not mail a copy.

Use the following information to assist you in avoiding processing delays and applying for credit faster.

If you are filing on paper, use a calculator. Review the entries you made on each line for accuracy and verify your calculations.

File and pay based on the frequency the Department has assigned you.
Doing otherwise may lead to penalties for unfiled returns or late payments. If you had no activity for the filing period, or if no tax is due, you still must file a return reporting this.

Make sure you use the correct version of the form you are filing.
Forms are updated to comply with new laws or to improve taxpayer understanding. Each time an update is made, a new revision date is put on the form. This date is shown in parentheses, typically at the bottom of the form. Example: a form updated in April 2014 would show (R-04/14). The most current version of all forms is available for download at our website,

Vehicle, watercraft, and aircraft returns

(includes ST-556, RUT-25, RUT-50, and RUT-75)

Do not make copies of your return to use for multiple transactions.
All vehicle, watercraft, and aircraft returns have a unique identifying number (Transaction, MV, PV, AV, or AW number) at the top that should not be duplicated.

When filing an amended return, you must include the unique identifying number (Transaction, MV, PV, AV, or AW number) from the original return that you are changing or correcting.

Complete all date fields with the required entry.

  • Form ST-556 requires a date of delivery for the vehicle. This date establishes the due date of the return.
  • Form RUT-25 requires both a purchase date and the date you brought the vehicle into Illinois. Even if those dates are the same, both fields must be completed with a valid entry.
  • Form RUT-50 requires a purchase date. This must be completed with a valid entry.

If you leave date fields blank or enter an invalid date, your return may be delayed and may lead to bills or correspondence requiring you to pay or to provide the correct information.

Provide all the required information on the return.

  • If the return requires a Social Security number field, you must complete with your full SSN.
  • All forms require identification numbers of the vehicle, watercraft, or aircraft (VIN, serial, hull, etc.). Verify that you have entered that number accurately.
  • Print information clearly.
  • Sales to exempt organizations require the entry of the Illinois Department of Revenue “E number”. You must obtain this from the buyer and include it on the return in order for us to process your return with this exemption.
  • Attach the bill of sale when required.
  • If you are directed to check a box, please be sure your selection is marked clearly and obviously.

Other sales and related tax returns

(includes ART-1, CMFT-1, PST-1, ST-1, ST-4, ST-8, and ST-14)

Submit only one original return per reporting period.
If you file electronically or if your preparer files the return for you, do not mail a second copy of your return. Sending us multiple returns for a single reporting period causes unnecessary delays in the processing of your return.

When using MyTax Illinois to file your return, make sure you submit the return.
The “Save” feature does not send your return to the Department. If you are finished with your return and you are ready to send it to the Department, you must click the “Submit” button and provide your password as your signature. A confirmation page will appear verifying that your return has been submitted. The easiest way to make a payment for this return is from the confirmation screen. Click on the “Proceed to payment” button at the top of the confirmation screen to complete the payment process.

Fairs, festivals, flea markets, craft shows, antique malls and other similar venues may require special reporting of Form ST-1.
Make sure you know your reporting and payment requirements if you sell items at special events. PIO-28 at is a good resource to reference for these situations.

Businesses registered to file and pay using Form ST-1 must include any use tax liability they may owe as part of their filing.
Form ST-44 is for individuals and businesses that are not required to be registered to file Form ST-1.

Verify all payments before submitting.

  • Payments are applied to your liabilities based on the information that you include with your payment.
    • If you are paying electronically, make sure you select the correct period for which you are paying.
    • If you are mailing a check, be sure to include the period for which you are paying, along with your account ID on the check.
  • MyTax Illinois has two payment options. Make sure you understand what is actually being paid and when. When you select to ‘Make a payment’ or ‘Pay multiple accounts’ several choices have to be made including period of payment and type of payment. After all selections have been made, a mock check appears on the screen with required fields needing to be completed. You have two choices at this time.
    • Debit payment – providing the requested bank information creates a ‘payment request’ in MyTax Illinois. You must enter your bank account number and routing number into the system and authorize a payment with your password. This payment is being submitted electronically, and you should not send us paper.
    • Mail payment – selecting the ‘Mail payment’ button at the top of the screen creates a printable payment voucher for you to use when mailing a payment. Mail payment DOES NOT submit an electronic payment. You must mail it with a check or money order to the address on the voucher

Verify the tax rate that you are using.

  • If you have multiple locations (or your only ST-1 sales location is a changing location), you must use the multi-site form associated with your tax return and attach a copy with your submission. This allows you to calculate tax based on the location of your sale using the correct rate.
    • ART-1 filers use ART-2.
    • CMFT-1 filers use CMFT-2.
    • ST-1 filers use ST-2.
    • ST-4 filers use ST-7.
  • You must notify us immediately about changes to your locations such as closing or adding a new one. This can be done using the ‘Maintain Locations’ link in your MyTax Illinois account or by contacting Central Registration directly.
  • Use the Tax Rate Database at to verify rates.

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