1. Illinois-specific invoice requirements
- Sales tax line: 6.25% state rate. Most services rendered in Illinois are exempt from sales tax — but materials, parts, and tangible goods are not. Services largely exempt; combined rates up to ~11% in Chicago.
- Late-fee cap: Illinois statute 815 ILCS 205/4 (Interest Act) caps interest on unpaid invoices at 1.5% per month. Spell out the rate in writing on every invoice and in your contract — courts won't enforce undisclosed fees.
- Written contract required: Illinois requires a signed agreement for any job over $1,000. Reference the contract number on the invoice.
- Right-to-cancel notice: Customers in Illinois get 72-hour cancellation rights on certain home-services contracts. Disclose this in your terms.
2. Architect line items + standard terms
Every architect invoice in Illinois should itemize work clearly. Standard architects use Net 30 terms with a 25% deposit required upfront.
- Schematic design phase — billed by flat.
- Construction documents phase — billed by flat.
- Hourly — billed by hour (~$195 default).
- Reimbursable expenses — billed by itemized.
3. Architect licensing in Illinois
State licensure (NCARB) required to call yourself an architect or stamp drawings. AIA contracts (B101, etc.) are industry-standard.
4. Send and follow up
Send the invoice the same day work completes. Use software that records open events and offers a one-click online payment so you don't need to chase a check by mail. Illinois customers expect digital payment options today — accepting card and ACH typically reduces days-to-paid by 30–50%.
Average invoice
$9,500
State
IL
Net terms
30 days
Deposit
25%
Illinois metro guides
Metro-specific guides include the combined sales-tax rate and local pricing benchmarks.