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OpenAccountants/Illinois/Illinois sales and use tax: 2026 rates, sourcing, nexus, service occupation tax and filing

Illinois sales and use tax: 2026 rates, sourcing, nexus, service occupation tax and filing

Illinois sales and use tax for 2026: Retailers' Occupation Tax and Use Tax at 6.25% (drugs 1%), no State tax on groceries from 1 January 2026 with a local 1% option, origin and destination sourcing, the $100,000 remote-seller threshold with no transaction test, marketplace facilitators, Service Occupation Tax methods, CRT-61 resale certificates, Form ST-1 filing, the 1.75% discount, penalties and interest.

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Key figures — Illinois, 2026

TaxWho owes itHow it works
Retailers' Occupation Tax (ROT)Retailers, on gross receipts from selling TPP at retailSection 2 of the ROT Act (35 ILCS 120)
Use TaxBuyers, for using in Illinois TPP bought at retail anywhereThe retailer collects it from the customer, which reimburses the retailer's ROT. If the retailer does not collect it, the customer pays IDOR directly (35 ILCS 105)
Service Occupation Tax (SOT)Servicepersons, only on TPP they transfer as part of a sale of service35 ILCS 115 in IDOR's publications. The service element is not taxed
Service Use Tax (SUT)Buyers, for using in Illinois TPP received as part of a service35 ILCS 110 in IDOR's publications

The full Guide

Figures are for tax year 2026, as they stand on 25 September 2026. They come from the Illinois Department of Revenue (IDOR) at tax.illinois.gov. Illinois "sales tax" is really two pairs of taxes: the Retailers' Occupation Tax (ROT) with the Use Tax, and the Service Occupation Tax (SOT) with the Service Use Tax (SUT). Three changes matter most for 2026: the State tax on groceries ended on 1 January 2026 (a local 1% grocery tax may apply instead), the 200-transaction test for remote sellers ended on 1 January 2026, and destination sourcing now reaches more sellers (IDOR bulletin FY 2026-03; IDOR bulletin FY 2026-12). A short section at the end covers 2025 periods.

Scope and who this is for

  • Retailers selling tangible personal property (TPP) in Illinois or to Illinois customers, deciding what rate to charge, which location's local taxes apply, and how to file Form ST-1.
  • Out-of-state sellers deciding whether they must register (remote retailers, marketplace sellers, marketplace facilitators), including sellers who registered only because of the old 200-transaction test.
  • Servicepersons (repairers, installers, and others) who transfer goods as part of a service and owe SOT on those goods.
  • Businesses that owe Use Tax because no Illinois tax was charged on their purchases.
  • Sellers accepting, and buyers giving, Form CRT-61 resale certificates.
  • Out of scope: vehicles and other titled or registered items (Forms ST-556 and RUT-25), motor fuel and prepaid sales tax on fuel, the Prepaid Wireless E911 Surcharge and ITAC Assessment, cannabis taxes, hotel taxes, and taxes that cities such as Chicago collect themselves. Detailed taxability of software is also out of scope; see "When to refuse or refer".

Ask the client first

  • Does the business have any physical presence in Illinois: an office, warehouse, inventory, employees, agents or other representatives, or its own delivery vehicles?
  • If it is outside Illinois: what were its gross receipts from sales of goods to Illinois purchasers in each rolling 12-month period ending 31 March, 30 June, 30 September and 31 December? Did it register in the past only because it made 200 or more transactions?
  • Does it sell through a marketplace? Has the marketplace facilitator certified (Form CRT-63) that it collects and remits Illinois tax? Is any of its inventory in an Illinois warehouse, and is that inventory used only for marketplace orders?
  • Is each sale fulfilled from Illinois inventory, or from outside Illinois? Where is the buyer's delivery address?
  • What does it sell: general merchandise, groceries, candy or soft drinks, prepared food, drugs or medical appliances, or services that include parts or materials? Does it offer seating for eating on the premises?
  • For servicepersons: are parts separately stated on the bill? What is the business's annual cost ratio (cost of goods transferred divided by total service income)?
  • What filing frequency has IDOR assigned, and has IDOR told it to pay quarter-monthly or to file and pay electronically?
  • Does it hold a CRT-61 (with an active Illinois account ID) or an exemption number for every untaxed sale?
  • Were any returns filed or paid late, or is any period under audit? Is the business a remote retailer with unpaid tax for sales between 1 January 2021 and 30 June 2026 (the amnesty below ends 31 October 2026)?

The method, step by step

  1. Decide whether the seller must register. A seller with physical presence in Illinois must register and collect. A remote retailer (no physical presence) must register and collect once it has $100,000 or more in cumulative gross receipts from sales of goods to Illinois purchasers in the preceding 12 months, tested at the end of each calendar quarter. From 1 January 2026 there is no transaction-count test (IDOR bulletin FY 2026-12).
  2. Classify each item. General merchandise is taxed at the State rate of 6.25%. Qualifying drugs and medical appliances are taxed at the State rate of 1%. Groceries carry no State tax from 1 January 2026, but a local 1% grocery tax may apply (Publication 113). Candy, soft drinks, alcohol and food prepared for immediate consumption are general merchandise.
  3. Decide where the sale is sourced. A sale made from an Illinois location, or filled from Illinois inventory, takes the rates at that location (origin). A sale made from outside Illinois by a retailer that must collect takes the rates at the Illinois delivery address (destination) (Publication 113).
  4. Look up the rate; do not memorise it. Use the MyTax Illinois Tax Rate Finder ("Search by Address" for destination sales) for the period of the sale. Local rates generally change on 1 January and 1 July (ROT page).
  5. Check the paperwork for untaxed sales. A resale needs the buyer's active Illinois registration or resale number and a certification, usually Form CRT-61. An exempt organisation must give its IDOR exemption number (ROT page).
  6. For services, work out the SOT base using one of the four methods below. The service element itself is never taxed (IDOR bulletin FY 2026-13).
  7. Accrue Use Tax on your own purchases for use in Illinois where no Illinois tax was paid, on the Form ST-1 for the period of purchase, or of removal from resale stock (Publication 113).
  8. File Form ST-1 (and Form ST-2 for multiple or destination sites) by the 20th of the month after the period, even with nothing to report. Take the 1.75% discount only if you file and pay on time (Form ST-1 instructions).
  9. Keep records for three and one-half years after filing, including full delivery addresses for destination sales (record-keeping page).

Rates, sourcing and thresholds for 2026

The four taxes (ROT page; Publication 113-SOT)

TaxWho owes itHow it works
Retailers' Occupation Tax (ROT)Retailers, on gross receipts from selling TPP at retailSection 2 of the ROT Act (35 ILCS 120)
Use TaxBuyers, for using in Illinois TPP bought at retail anywhereThe retailer collects it from the customer, which reimburses the retailer's ROT. If the retailer does not collect it, the customer pays IDOR directly (35 ILCS 105)
Service Occupation Tax (SOT)Servicepersons, only on TPP they transfer as part of a sale of service35 ILCS 115 in IDOR's publications. The service element is not taxed
Service Use Tax (SUT)Buyers, for using in Illinois TPP received as part of a service35 ILCS 110 in IDOR's publications

The Service Occupation Tax Act is 35 ILCS 115 and the Service Use Tax Act is 35 ILCS 110. The earlier version of this Guide had these two reversed.

From 1 January 2025, a lease of TPP (other than most titled or registered items) is a sale at retail, so lessors owe ROT on lease receipts (ROT page).

State rates (Publication 113; PIO-115)

CategoryState rate 2026Conditions
General merchandise6.25%Most TPP, including clothing, candy, soft drinks, alcohol, food prepared for immediate consumption, prewritten ("canned") software, grooming and hygiene products, and parts transferred with a service
Qualifying drugs and medical appliances1%Prescription and nonprescription medicines, including products whose label makes a medicinal claim ("medicated", "for relief of..."). Medical appliances that directly replace a malfunctioning part of the body. Not grooming and hygiene products
GroceriesNo State tax from 1 January 2026Food for human consumption to be eaten off the premises where sold. Not alcohol, cannabis-infused food, soft drinks, candy, or food prepared for immediate consumption. Local grocery tax may apply (next table)
Use Tax on your own purchases6.25% general merchandise; 1% drugs and medical appliancesIf you paid another state's tax at a lower rate, pay Illinois the difference

Groceries from 1 January 2026 (IDOR bulletin FY 2026-03; compliance alert CA-2026-01)

  • The State's 1% tax on groceries ended after 31 December 2025. Municipalities, and counties for their unincorporated areas, may impose a local grocery tax of exactly 1% by ordinance filed with and approved by IDOR.
  • An ordinance filed by 1 April takes effect on 1 July of the same year. One filed by 1 October takes effect on 1 January of the next year.
  • The existing local grocery tax in the Regional Transportation Authority (RTA) and Metro-East Mass Transit District (MED) areas continues. From 1 June 2026 the RTA is known as the Northern Illinois Transit Authority (NITA).
  • The retailer must check whether its location, or the delivery address for a destination sale, has a grocery tax. IDOR says retailers must remit the 1% tax "even if the tax was not collected from their customers".
  • Report groceries on the new Line 5c of Form ST-1 where a grocery tax applies. Where none applies (outside RTA and MED), include the receipts on Step 2, Line 1 and deduct them on Schedule A, Line 16.
  • From 1 January 2026, restaurants and other food vendors no longer owe Use Tax on the cost of meals given free to employees or customers. They still owe it on general merchandise given away, such as candy and soda (Publication 113).

Food boundaries (PIO-115)

ItemTreatmentCondition
CandyGeneral merchandiseSugar, honey or other sweeteners combined with chocolate, fruit, nuts or other ingredients, "in the form of bars, drops, or pieces"
Product containing flour (cookies, chocolate-covered pretzels, granola bars with flour)Groceries"Candy" does not include any preparation that contains flour, whatever the type of flour
Product that requires refrigerationGroceriesOnly if it requires refrigeration. A candy bar sold frozen but not needing it is still candy
Water without sweeteners; juice over 50% fruit or vegetable; milk drinksGroceriesSweetened drinks otherwise are soft drinks (general merchandise)
Sandwiches in a deli caseGroceriesA sandwich made to the customer's order, or hot food, is general merchandise
Any food where the seller provides seatingPresumed general merchandiseRebutted only if the eating area is separate and the seller records the two kinds of sales separately
Vitamins and supplementsGroceriesOnly if the label makes no medicinal claim. With a medicinal claim they are drugs at the State rate of 1%

Local taxes: look them up (ROT page; Publication 113)

  • The combined rate is the State rate plus local taxes that IDOR collects: home rule and non-home rule municipal taxes, RTA (NITA) and MED taxes, county public safety, facilities and transportation taxes, county school facility taxes, park district and business district taxes.
  • Home rule, non-home rule, county school facility, county public safety and similar taxes, and Metro-East park and recreation taxes, do not apply to drugs, groceries, medical appliances, or titled or registered items.
  • This Guide gives no local rates because they vary by address and change twice a year. Use the MyTax Illinois Tax Rate Finder, or the machine-readable address files for destination sales.
  • Local governments may also impose taxes that IDOR does not collect (for example, taxes a city administers itself). Contact the city or county for those.

Sourcing: origin or destination (Publication 113; IDOR bulletin FY 2025-10)

Seller and saleRate used
Illinois retailer, sale made from its Illinois locationOrigin: rates at that location
Sale made from outside Illinois but filled from Illinois inventoryOrigin: rates at the inventory location
Retailer with a place of business in Illinois selling from outside Illinois (from 1 January 2025)Destination: rates at the Illinois delivery address
Remote retailer at or over the thresholdDestination
Marketplace facilitator at or over the threshold, for marketplace sellers' salesDestination
Marketplace facilitator's own salesOrigin if filled from Illinois inventory or selling activity is in Illinois; otherwise destination
Leases with recurring payments and delivery to the customerDestination
Servicepersons with a place of business in Illinois transferring goods from outside Illinois (from 1 January 2026)Destination (FY 2026-13)

For destination sales, register a changing-location tax site for each city or county you deliver to, before filing the return for that period, and report each site on Form ST-2 (IDOR bulletin FY 2025-10).

The 15% undetermined-location rate. From 1 January 2026, if a seller cannot show where destination sales went, IDOR taxes those gross receipts at 15%. IDOR may use this rate in an audit of any period, including periods before January 2026. Keep, for each destination sale, the customer's name and billing address, the exact delivery address (street, city, county, state, ZIP), and proof of where the goods shipped from (IDOR bulletin FY 2026-12).

Remote retailers and marketplace facilitators (IDOR bulletin FY 2026-12; Publication 113-D)

Rule2026 position
Threshold$100,000 or more in cumulative gross receipts from sales of TPP to Illinois purchasers. Exactly $100,000 meets it
Transaction testNone from 1 January 2026 (200 or more transactions counted before)
LookbackPreceding 12 months, tested at the end of March, June, September and December
Once overCollect State and local ROT at destination rates on all retail sales to Illinois purchasers and file returns for one year, then re-test (ROT page)
Registered only under the old 200 testReview the 12 months ending 31 December 2025. If under $100,000, stop remitting ROT for remote sales from 1 January 2026; IDOR moves the account to "voluntary use tax". Any destination ROT collected after that must be refunded or reported as Use Tax, with anything above 6.25% reported as excess tax
Under the thresholdNo Illinois collection duty. The seller may register voluntarily and collect 6.25% Use Tax as a courtesy
Marketplace facilitatorA person who lists a third party's goods and collects payment (directly or through others). At or over the threshold, it is the retailer for every sale on its marketplace, at destination rates
Marketplace sellerA seller whose sales all go through facilitators that meet the threshold may close its Illinois account; Form CRT-63 proves the facilitator will collect (FY 2025-10)
Inventory in a facilitator's Illinois warehouseNo physical presence if used only for marketplace orders. If it also fills the seller's own orders, the seller has physical presence and owes origin-based ROT on those sales

IDOR's general ROT page still describes the 200-transaction test. The bulletin FY 2026-12 is later and says the test "no longer applies". Follow the bulletin, and note the conflict if a client relies on the ROT page.

Service Occupation Tax: summary (IDOR bulletin FY 2026-13; Publication 113-SOT)

SOT applies only when a serviceperson transfers goods as part of a sale of service. A serviceperson calculates its tax in one of four ways:

MethodBaseWho may use it
1. Separately stated selling priceSOT on the separately stated price of the goods transferredAny serviceperson. The selling price cannot be less than cost price
2. Half the billSOT on 50% of the entire billWhere no charge for the goods is separately stated, the selling price is 50% of the bill, but never less than cost price
3. Cost price, SOTSOT on the serviceperson's cost price of the goodsA de minimis serviceperson that is registered, or required to be registered, as a retailer under Section 2a of the ROT Act
4. Cost price, Use TaxUse Tax on cost price, paid to the supplier or self-assessedA de minimis serviceperson not otherwise required to register. Not available to one whose only Illinois presence is meeting the $100,000 services threshold if it makes any retail sales to Illinois purchasers
  • De minimis serviceperson: annual cost ratio below 35% (75% for servicepersons transferring prescription drugs or engaged in graphic arts production). The cost ratio compares the annual cost of goods transferred with total annual service income.
  • Services threshold: $100,000 in cumulative gross receipts from sales of service to Illinois purchasers over the preceding 12 months, tested quarterly. From 1 January 2026 there is no 200-transaction test for servicepersons or service marketplaces.
  • Service marketplace facilitators at or over the $100,000 services threshold owe SOT on 50% of the entire billing for every service sale through the marketplace that transfers goods to an Illinois purchaser.
  • The SOT rate on goods follows the same general merchandise, drug and local rules as ROT; look up the location's rate.

Filing frequency and payments (Form ST-1 instructions; Publication 113)

Average monthly liabilityFrequency IDOR may assign
Greater than $200Monthly
Between $50 and $200Quarterly
Less than $50Annual
$20,000 or moreQuarter-monthly payments on the 7th, 15th, 22nd and last day of each month, made electronically; IDOR notifies you

New registrants start as monthly or quarterly filers. IDOR reviews accounts each year and writes if the frequency changes. Taxpayers whose average tax due is at least $20,000 annually must pay electronically, and IDOR's page says ST-1 must be filed electronically if "annual gross receipts average $20,000 or more"; IDOR notifies taxpayers of both mandates.

What is taxable: boundary and exception table

Exemptions and exclusions (ROT page; Publication 113-D)

ItemStatusCondition
Sales for resaleNot taxedBuyer gives an active Illinois registration or resale number and certifies resale (usually CRT-61). Without both, the sale is presumed not for resale
State, local and federal governmentsExempt
Exclusively charitable, religious or educational organisationsExemptThe organisation must hold an IDOR exemption number ("E-number") and give it to the seller
Newspapers and magazinesExempt
Sales to out-of-state buyers (interstate commerce)ExemptSpecial limits apply to vehicles and trailers titled in states without a reciprocal exemption
Manufacturing and assembling machinery and equipmentExemptUsed primarily in manufacturing or assembling goods for sale or lease
Production agriculture machinery and equipmentExemptListed with manufacturing on the ROT page; check the use conditions
Rolling stock for interstate carriers for hireExemptE.g. semi-tractor trailers, railroad cars
Enterprise zone building materials and purchasesExemptOnly with a Certificate of Eligibility or certification from the Department of Commerce and Economic Opportunity
Legal tender, qualifying medallions and gold bullion; fuel for international flightsExempt
SNAP (food stamp) purchasesExempt
Clothing and footwearTaxable at 6.25%No general exemption. Only the 2026 back-to-school holiday below reduced it
Prewritten ("canned") softwareTaxable at 6.25%General merchandise. For custom software, SaaS and digital products, see "When to refuse or refer"
Repair labor and other servicesNot taxedOnly goods transferred with the service are taxed (SOT)

Resale certificates: Form CRT-61 (Form CRT-61; ROT page)

  • The buyer ticks one box: registered with IDOR as a retailer or reseller (with its Illinois account ID), or an out-of-state purchaser that will resell and deliver the goods only outside Illinois (with its other state's registration).
  • It covers one purchase (describe the property or invoice), all purchases from the seller (full blanket), or a stated percentage of single-item-type purchases (percentage blanket).
  • The seller must check that the buyer's Illinois account ID is valid and active, using "Verify a Registered Business" in MyTax Illinois.
  • A buyer that uses the goods other than for resale owes tax on their purchase price, and may face penalties and interest.
  • Keep, for every deduction on the return, the buyer's name and address, the type and date of the transaction, the amount, and the evidence that it was not taxable (record-keeping page).

Back-to-school holiday, 7 to 16 August 2026 (IDOR bulletin FY 2026-30)

  • The State portion fell by 5% (from 6.25% to 1.25%) on qualifying clothing and footwear priced below $125 per item, and on qualifying school supplies (no price limit). Local taxes still applied.
  • The price test is after unreimbursed coupons and markdowns. Items sold as one unit (a pair of shoes) cannot be split. Claim the credit on Schedule K-12 with Form ST-1.

Worked cases (IDOR bulletin FY 2026-12; Form ST-1 instructions)

Examples use the State rate only unless a combined rate is given. In practice, add the local rate from the Tax Rate Finder.

  1. Remote retailer after the transaction test ended (FY 2026-12). An Oregon seller with no Illinois presence made 450 sales worth $80,000 to Illinois buyers in the 12 months to 31 March 2026. Before 2026, 200 or more transactions would have required collection. In 2026 the only test is $100,000 or more, so it has no duty from that quarter's test. In the 12 months to 30 June 2026 its sales reach $104,000, which is $100,000 or more. It must register, collect State and local ROT at the rate for each delivery address, and file for one year. IDOR's pages reviewed here give no start date after the quarter end; confirm it with IDOR's Central Registration Division.
  2. Groceries, candy and drugs (PIO-115; FY 2026-03). A shop outside the RTA and MED areas, with no seating, sells $200 of groceries, a $20 box of granola bars containing flour, a $40 box of chocolate bars without flour, and $10 of aspirin. The granola bars contain flour, so they are groceries: $200 + $20 = $220 of groceries. In a town with no grocery ordinance: no State or local tax on the $220. Chocolate is candy: 40 x 6.25% = $2.50 State tax, plus local general merchandise taxes. Aspirin is a drug: 10 x 1% = $0.10 State tax. If the town has a 1% grocery ordinance: 220 x 1% = $2.20 local grocery tax, which the shop owes whether or not it collected it.
  3. Service Occupation Tax methods (FY 2026-13; Publication 113-SOT). A repair shop bills $500 labor and $300 parts, separately stated. Method 1: tax on $300 only, 300 x 6.25% = $18.75 State SOT; the $500 labor is not taxed. If the bill just says $800 with no split, method 2 applies: 800 x 50% = $400, and 400 x 6.25% = $25.00. If the parts cost the shop $450, the base cannot be less than cost price, so the base is $450 and 450 x 6.25% = $28.13. A de minimis shop registered under Section 2a (cost ratio below 35%) using method 3 on parts that cost $120 owes 120 x 6.25% = $7.50.
  4. Discount, cap and a late return (Form ST-1 instructions; Publication 103; interest rates). A monthly filer owes $5,000 for August 2026, due 21 September 2026 (20 September is a Sunday). Filed and paid on time: discount 5000 x 1.75% = $87.50, net $4,912.50. A larger filer owing $80,000 would compute 80000 x 1.75% = $1,400 but the cap limits it to $1,000. If the $5,000 return is filed and paid 12 days late: no discount; late-payment penalty 5000 x 2% = $100 (1 to 30 days late); late-filing penalty is the lesser of $250 or 2% of the tax, so $100; interest at 7% simple, 5000 x 7% / 365 x 12 = $11.51.
  5. Use Tax on a business purchase (Publication 113). A registered Illinois retailer buys $2,000 of office equipment from an out-of-state vendor that charged no Illinois tax. It reports Use Tax on its Form ST-1 for that month: 2000 x 6.25% = $125.00. If it had paid another state's tax at 4%, it would owe Illinois the difference: 6.25% - 4% = 2.25%, and 2000 x 2.25% = $45.00.
  6. Back-to-school holiday (FY 2026-30). On 10 August 2026, in a location whose normal combined rate is 9.75%, a $100 pair of jeans qualifies: rate 9.75% - 5% = 4.75%, tax 100 x 4.75% = $4.75. A $140 pair of shoes does not qualify (not below $125): 140 x 9.75% = $13.65.

When to refuse or refer

  • Software other than canned software, SaaS, streaming and digital downloads. IDOR's pages reviewed here class prewritten software as general merchandise but do not settle SaaS or custom software. The earlier version of this Guide said pure SaaS is not taxable, citing an IDOR letter; that was not confirmed on the sources reviewed. Check 86 Ill. Adm. Code 130.1935 and IDOR letter rulings, or refer.
  • Taxes IDOR does not collect, such as a city's own amusement, restaurant or soft drink taxes (except the Chicago soft drink ROT, which IDOR does collect). Refer to the city or county.
  • Vehicles, watercraft, aircraft, trailers and mobile homes (Forms ST-556, RUT-25, RUT-50, RUT-75), and motor fuel prepaid sales tax.
  • Audits, the 15% undetermined-location rate, and appeals to the Illinois Independent Tax Tribunal or circuit court (IDOR bulletin FY 2026-12).
  • Remote retailer amnesty decisions with large exposure. The 2026 Remote Retailer Tax Amnesty runs 1 August to 31 October 2026 for sales between 1 January 2021 and 30 June 2026. It uses simplified rates of 9% (general merchandise) and 1.75% (items normally at the State 1% rate), waives penalties and interest if paid in full or under a completed plan, and does not waive books-and-records penalties, bad check penalties or lien fees (FY 2026-28).
  • Exemption claims needing certificates beyond CRT-61 and E-numbers (manufacturing, farm, enterprise zone, high impact business). Check the use conditions and documents in PIO-101 before relying on them.
  • A client that wants a single "Illinois rate". There is none; refuse to quote one without the address and period.

Filing and payment

Registration (Publication 113-D)

  • Register through MyTax Illinois (Form REG-1). The Certificate of Registration expires after one year and renews automatically while the account is compliant.
  • A buyer of the major part of another business's stock, fixtures or equipment must file Form CBS-1 at least ten days before the sale, or risk liability for the seller's unpaid tax.

Due dates and the return (Form ST-1 instructions; ROT page)

FilerDue date
Monthly20th of the following month
Quarterly20th of the month after the calendar quarter: 20 April, 20 July, 20 October, 20 January
Annual20 January of the following year
Any due date on a weekend or State holidayNext business day
  • File a signed ("processable") Form ST-1 for every period, including zero returns. Attach Form ST-2 for multiple sites and all destination sites.
  • Over-collected tax that is not refunded goes on the excess tax line. Correct errors with Form ST-1-X.
  • Individuals and unregistered businesses owing Use Tax file Form ST-44: by 15 April of the next year if $600 or less is owed for the year; if more than $600, by the last day of the month after the month of purchase (ROT page).
  • IDOR uses the U.S. Postal Service postmark to decide whether mailed returns and payments are on time; private postage meters do not count.

Retailers' discount (Form ST-1 instructions; Publication 113)

  • 1.75% of the tax due, or $5 per calendar year, whichever is greater.
  • For returns due on or after 1 January 2025 the discount is capped at $1,000 per month. IDOR states the cap per month; quarterly and annual filers should confirm with IDOR how it applies to a multi-month return.
  • Only if the return and payment are on time. A taxpayer required to file electronically (and without a waiver) gets the discount only if it files electronically on time and pays on time.
  • A late filer is assessed for the discount it took, plus penalty and interest.

Penalties and interest (Publication 103; interest rates)

PenaltyAmount
Late filing, first tierLesser of $250 or 2% of the tax required to be shown, reduced by timely payments and credits
Late filing, second tier (not filed within 30 days of a notice of nonfiling)Greater of $250 or 2% of the tax shown, without regard to payments; maximum $5,000; due even if no tax is owed
Late payment2% if 1 to 30 days late; 10% if 31 or more days late
Unpaid after an audit starts15%
Unpaid within 30 days after an audit-prepared amended return or waiver20% (also applies if paid under protest or later claimed back)
Negligence20% of the deficiency from the negligent act
Fraud50% of the deficiency
Failure to keep or produce books and records$1,000 for the first failure, $3,000 for each later one
InterestSimple interest at the federal underpayment rate, reset each 1 January and 1 July: 7% for 1 January 2025 to 31 December 2026. It runs from the day after the due date

A late-filing or late-payment penalty may be abated for reasonable cause if you give IDOR a detailed explanation and documents.

Records (record-keeping page)

  • Keep records that support receipts for three and one-half years after filing the original or amended return. If IDOR has issued a Notice of Tax Liability or Final Notice of Tax Due, keep them until that liability is final or paid.
  • Records must be available during business hours, in English, and kept in Illinois unless IDOR agrees otherwise. They must separate taxable from non-taxable sales.
  • The time limits for IDOR to assess tax (for example, where no return was filed or there was fraud) are in the ROT Act, not in the pages reviewed here. Check them before relying on a period being closed.

2025 periods (for amended or audited 2025 returns) (IDOR bulletin FY 2026-03; IDOR bulletin FY 2026-12)

  • Groceries: through 31 December 2025, qualifying food was taxed at the State rate of 1% plus local taxes. Use the pre-2026 Form ST-1 and ST-2 revisions for those periods.
  • Remote threshold: for lookback periods ending on or before 31 December 2025, a remote retailer or marketplace facilitator was over the threshold with either $100,000 or more in gross receipts or 200 or more separate transactions.
  • Destination sourcing: from 1 January 2025, retailers with an Illinois place of business selling from outside Illinois moved from collecting Use Tax to destination ROT. Servicepersons moved on 1 January 2026.
  • Discount cap: the $1,000 monthly cap applies to returns due on or after 1 January 2025, so it applies to every 2025 return.
  • Interest: 7% applied throughout 2025 (interest rates).
  • The 15% undetermined-location rate may be applied in audits of 2025 and earlier periods.

Completion checklist (ROT page)

  • Physical presence checked; for remote sellers, each quarter's 12-month gross receipts tested against $100,000 or more, with no transaction test for 2026 periods.
  • Sellers registered only under the old 200 test reviewed against the 12 months to 31 December 2025.
  • Each item classified: general merchandise, drug or medical appliance, groceries (flour and refrigeration tests for sweets), prepared food.
  • Each sale sourced (origin or destination) and the rate taken from the Tax Rate Finder for that address and period, including any local 1% grocery tax.
  • Delivery addresses kept for every destination sale, so the 15% rate cannot be applied.
  • SOT base chosen from the four methods, and the de minimis cost ratio tested.
  • CRT-61 or E-number on file for every untaxed sale; buyer's account ID verified as active.
  • Use Tax accrued on untaxed purchases and on items taken from resale stock.
  • Form ST-1 (and ST-2) filed by the 20th, including zero returns; 1.75% discount taken only when on time and within the $1,000 cap.
  • Remote retailer amnesty considered before 31 October 2026 where old periods are unpaid.
  • Records kept for three and one-half years after filing.

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