Using the state rate and ignoring local tax
The state rate is 6.25% but the average customer pays 8.98%. Under-collecting leaves you funding the difference out of your own margin.
USD · 8.98% average combined rate · Reviewed September 2026
Illinois Invoice Generator & Sales Tax Guide
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Illinois taxes the retailer's occupation rather than the sale itself, and home-rule municipalities — Chicago in particular — add enough on top to push combined rates into the top ten nationally.
Illinois sales tax rates
Illinois charges retailers' occupation tax (sales tax) at 6.25% statewide. Local jurisdictions add 2.73% on average and up to 4.75%, so the state rate on its own is rarely the number that belongs on an invoice.
| Statewide rate | 6.25% |
|---|---|
| Average local add-on | 2.73% |
| Highest local add-on tracked | 4.75% |
| Average combined rate | 8.98% |
| Rank by combined rate | 8th highest of 50 states |
Local rates in Illinois
Local sales tax in Illinois is set by cities, counties and in some cases special districts whose boundaries do not follow postal areas. Two customers in the same city can sit in different districts, which is why an address-based lookup beats a remembered rate.
The practical approach: look the rate up at the customer's delivery or service address using the Illinois Department of Revenue lookup, record which rate you used on the invoice, and re-check it when local taxes are renewed or introduced.
We publish the statewide rate and the state's average and maximum local add-ons here rather than a rate for every city, because city-level rates change often enough that a stale figure on this page would be worse than no figure at all.
What to put on a Illinois invoice
- The word Invoice and a unique invoice number
- Your business name, address, email and phone
- The customer's legal name and Illinois billing address
- Invoice date and a calendar due date, not just Net 30
- A line for each item or service with quantity and rate
- Any retailers' occupation tax (sales tax) shown on its own line with the rate used
- How to pay — ACH details, check payee or a payment link
- A purchase order number where the customer issued one
- Your state tax permit number where the state expects it
- A reference to an exemption or resale certificate on exempt sales
Registering and filing in Illinois
Sellers with a physical presence in Illinois — premises, staff, stock or regular on-site work — generally register with the Illinois Department of Revenue before their first taxable sale. Remote sellers register once their sales into the state cross the state's economic nexus threshold.
Filing frequency is set by the state and usually depends on how much tax you collect: larger collectors file monthly, smaller ones quarterly or annually. The Illinois Department of Revenue sets and notifies your frequency — do not assume it stays the same as your volume grows.
We deliberately do not publish thresholds, filing deadlines or penalty amounts on this page. Those numbers change, and the only copy worth relying on is the one on the state's own site, linked below.
Exempt sales and certificates
Resale, manufacturing, non-profit and government exemptions all exist in Illinois, and each one depends on a valid certificate from the buyer, not on the buyer's word. Collect the certificate before you issue a zero-tax invoice.
Reference the certificate on the invoice rather than silently leaving tax off. A tax line of $0.00 with a note explaining why is far easier to defend in an audit than an invoice with no mention of tax at all.
Example Illinois invoice
A contractor billing a Illinois customer for equipment and labour, showing how the tax line sits under the subtotal.
| Description | Qty | Rate | Amount |
|---|---|---|---|
| Equipment supplied and installed | 1 | $1,600.00 | $1,600.00 |
| On-site labour | 8 | $100.00 | $800.00 |
| Subtotal | $2,400.00 | ||
| Illinois retailers' occupation tax (sales tax) at the 8.98% average combined rate | $215.52 | ||
| Total due — Net 30 | $2,615.52 | ||
Common Illinois invoicing mistakes
Charging tax without being registered
Collecting retailers' occupation tax (sales tax) before you are registered creates a liability with no account to remit it to, and the customer cannot reclaim it.
Assuming services are treated like goods
Taxability of services varies widely between states and within them. Confirm the treatment of your specific service with the Illinois Department of Revenue rather than copying what a supplier in another state does.
Leaving the due date implied
Write both the terms and a calendar date. In a corporate payment run, an ambiguous due date always resolves in the payer's favour.
Filing the certificate nowhere
Exemption and resale certificates are what justify a zero-tax invoice years later. Store them alongside the invoice, not in an inbox.
Sending to your day-to-day contact only
Your contact commissioned the work; a different inbox pays for it. Ask for the accounts payable address at the start.
Illinois invoicing FAQs
What is the sales tax rate in Illinois?
The statewide rate is 6.25%. Local jurisdictions add 2.73% on average and up to 4.75% where local taxes are highest, giving an average combined rate of 8.98% — the 8th highest average combined rate in the country. Figures are from the Tax Foundation's midyear 2026 table; always confirm the rate for your customer's exact address with the Illinois Department of Revenue.
Do I have to charge Illinois retailers' occupation tax (sales tax) on my invoices?
Only if you are registered in Illinois and what you sell is taxable there. Registration is triggered by physical presence or by crossing the state's economic nexus threshold for remote sellers. Taxability of services in particular varies, so check the position for your specific work with the Illinois Department of Revenue before adding a tax line.
Does Illinois have local city or county sales taxes?
Yes. Local add-ons average 2.73% and reach 4.75% in the highest jurisdictions, so the state rate alone is rarely the rate you should show. Use the Illinois Department of Revenue address-based rate lookup for the customer's delivery address.
Is a specific invoice format required in Illinois?
There is no prescribed commercial invoice template in Illinois. What matters is that the invoice identifies both parties, describes the supply, shows the amount due, shows any retailers' occupation tax (sales tax) separately, and can be reconciled with your returns and records.
Where do I register for Illinois retailers' occupation tax (sales tax)?
Through the Illinois Department of Revenue, which runs registration, filing and rate lookups for Illinois. Its website is linked in the official sources section on this page.
Can I invoice a Illinois customer from another state or country?
Yes — the invoice itself is the same document. The question is whether your sales into Illinois create a registration obligation there. Remote sellers can be required to register once they exceed the state's economic nexus threshold, so track your sales by state.
Official sources
Last reviewed September 2026.
- Illinois Department of Revenue
The primary authority for Illinois registration, rates, filing and exemption rules.
- Tax Foundation — State and Local Sales Tax Rates, Midyear 2026
Secondary source for the statewide, average local and combined rate figures shown above.
- Federation of Tax Administrators — state tax agencies
Directory used to locate each state's official tax agency.
- IRS — small business and self-employed tax center
Federal guidance on business income, record-keeping and Form W-9.
Related tools and reading
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