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. Mobile App Developer line items + standard terms
Every mobile app developer invoice in Illinois should itemize work clearly. Standard mobile app developers use Net 30 terms with a 33% deposit required upfront.
- Sprint / milestone — billed by flat.
- Hourly — billed by hour (~$165 default).
- App Store submission — billed by flat.
- Maintenance retainer — billed by flat.
3. Mobile App Developer licensing in Illinois
No license required. App Store and Play Store policies must be honored.
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
$8,500
State
IL
Net terms
30 days
Deposit
33%
Illinois metro guides
Metro-specific guides include the combined sales-tax rate and local pricing benchmarks.