In this article
- Quick facts: Filing for sales tax in Illinois
- When to file and pay Illinois sales tax
- Illinois sales tax filing deadlines
- How to prepare your Illinois sales tax return
- How to complete and file an Illinois sales tax return
- How to pay sales tax in Illinois
- What happens after filing and paying Illinois sales tax
- Late filing penalties and interest
- Getting third-party help with sales tax filing
- Sales tax filing in other states
If you are registered for Illinois sales tax, you must file returns and pay any tax due according to the filing frequency assigned by the Illinois Department of Revenue. This guide focuses on the filing and payment process most relevant to remote sellers and out-of-state businesses using MyTax Illinois. Illinois applies destination-based sourcing for remote sellers, and digital goods and SaaS are taxable at the state level.
For broader information about Illinois sales tax rules, rates, and nexus, see the Illinois Sales Tax Guide. For details on how to register for an Illinois sales tax permit, see the Illinois Sales Tax Registration Guide.
Quick facts: Filing for sales tax in Illinois
Key information about filing Illinois sales tax returns, including filing frequency, deadlines, and payment options.
| Fact | Detail |
|---|---|
| Filing frequency | Monthly, quarterly, or annually |
| Filing deadline | The 20th day after the period ends |
| State tax rate | 6.25% (local rates may apply on top) |
| Filing portal | MyTax Illinois |
| Zero returns required | Yes |
| Digital goods and SaaS | Taxable |
When to file and pay Illinois sales tax
The Illinois Department of Revenue will assign you a filing frequency (monthly, quarterly, or annually) after you register for a sales tax permit. Businesses with higher sales tax liabilities are assigned more frequent filing periods.
Illinois sales tax returns and payments are due at the same time, by the 20th of the month following the end of the filing period. If the 20th falls on a weekend or holiday, the due date moves to the next business day.
Illinois sales tax filing deadlines
Illinois monthly filing due dates
Reports are due on the 20th of the month following the reporting month.
| Month | Filing Deadline |
|---|---|
| January | February 20 |
| February | March 20 |
| March | April 20 |
| April | May 20 |
| May | June 20 |
| June | July 20 |
| July | August 20 |
| August | September 20 |
| September | October 20 |
| October | November 20 |
| November | December 20 |
| December | January 20 |
Illinois quarterly filing due dates
| Quarter | Filing Deadline |
|---|---|
| Q1 (January 1, March 31) | April 20 |
| Q2 (April 1, June 30) | July 20 |
| Q3 (July 1, September 30) | October 20 |
| Q4 (October 1, December 31) | January 20 |
Illinois annual filing due date
Reports for the previous calendar year are due on January 20.
Important note: Zero returns
Once you have an Illinois sales tax permit, you are required to file a return for every assigned period, even if you had no sales or no tax due. When no sales tax was collected, file a zero return through MyTax Illinois.
How to prepare your Illinois sales tax return
Before working on your sales tax return, collect all sales information for the tax period.
Sales transactions
You need to know your total gross sales to Illinois buyers and your taxable sales. Illinois taxes digital goods and SaaS at the state rate of 6.25%. Remote sellers use destination-based sourcing, meaning you charge the rate applicable at the buyer's location.
Key reporting figures
In addition to your gross Illinois sales, filing a return requires:
- Total sales and income
- Taxable sales by type (different product categories may have different rates)
- Non-taxable sales and exemptions (for example, sales to resellers with a valid resale certificate)
- Deductions and adjustments
- Total sales tax collected from customers during the filing period
How to complete and file an Illinois sales tax return
Illinois sales tax returns are filed electronically through MyTax Illinois and must be reported in US dollars. Paper filing on Form ST-1 is available for businesses with an annual liability under $20,000, but online filing is strongly recommended.
Step-by-step: file an Illinois sales tax return
1. Collect all necessary information
Gather your sales records for the tax period. Note any taxable sales of digital goods or SaaS and ensure they are included at the correct rate for the buyer's location in Illinois.
2. Log in and file online
- Log in to MyTax Illinois.
- Navigate to your Sales Tax account.
- Select the filing period you want to file.
- Enter your gross sales, taxable sales by category, exemptions, and total tax collected.
- Review and submit your return.
3. Receive confirmation
After submitting, you will receive a confirmation number. Save this as your record of filing.
How to pay sales tax in Illinois
Illinois requires electronic payment for most businesses. You can pay directly within MyTax Illinois after filing your return. Accepted payment methods include:
- Electronic bank transfer (ACH debit)
- Credit card (where available through MyTax Illinois)
Payment and filing are due at the same time. Submitting your return without paying the amount due will still result in penalties and interest.
Timely filing discount
Illinois offers a discount of 1.75% of the tax paid, or $5 per calendar year, whichever is greater, for returns filed and paid on time. This incentive rewards businesses that stay current with their compliance obligations.
What happens after filing and paying Illinois sales tax
After filing and paying, keep a copy of your return and payment confirmation for your records.
- Save your filing confirmation and payment receipt
- Keep records supporting the reported amounts (invoices, transaction logs)
- Continue filing according to your assigned frequency
- File a zero return for any period with no taxable sales
➡ Need help understanding Illinois sales tax rules, rates, and nexus? See the Illinois Sales Tax Guide
➡ Need to register for Illinois sales tax? See the Illinois Sales Tax Registration Guide
Late filing penalties and interest
If you miss an Illinois sales tax filing deadline, file as soon as possible. Failure to file returns and remit collected tax on time results in penalties and interest charges that increase the longer you wait.
For current penalty rates and interest charges, refer to the Illinois Department of Revenue website.
Getting third-party help with sales tax filing
Quaderno can simplify your Illinois sales tax compliance by generating detailed tax reports and handling the filing process on your behalf. Connect your sales data and Quaderno manages the submission to the Illinois Department of Revenue, ensuring timely and accurate filing.
Sales tax filing in other states
- Arizona Sales Tax Filing Guide
- California Sales Tax Filing Guide
- Florida Sales Tax Filing Guide
- Georgia Sales Tax Filing Guide
- Kentucky Sales Tax Filing Guide
- Massachusetts Sales Tax Filing Guide
- New Jersey Sales Tax Filing Guide
- New York Sales Tax Filing Guide
- Ohio Sales Tax Filing Guide
- Pennsylvania Sales Tax Filing Guide
- Rhode Island Sales Tax Filing Guide
- South Carolina Sales Tax Filing Guide
- Texas Sales Tax Filing Guide
- Virginia Sales Tax Filing Guide
- Washington DC Sales Tax Filing Guide
Need help filing across multiple states?
Watch our webinar: US Sales Tax Registration & Filing Tips + AMA. Learn how international sellers register, file, and manage US sales tax compliance across multiple jurisdictions.
Note: At Quaderno we love providing helpful information and best practices about taxes, but we are not certified tax advisors. For further help, or if you are ever in doubt, please consult a professional tax advisor or the tax authorities.
