What does Illinois’s prompt payment law require on private construction?

In Illinois, an owner pays an approved payment application within 15 calendar days of approval (an application is deemed approved 25 days after receipt unless the owner gives a written statement of what is withheld and why), a contractor pays its subcontractor within 15 calendar days of being paid, and a late payment carries 10% a year interest, though the law excludes public contracts and homes of 12 or fewer units. The Act covers contracts to design, build, alter, improve or repair Illinois real property, except contracts paid with public funds and work on single family homes or buildings of 12 or fewer units. An owner who finds part of the work not done to the contract may withhold only the reasonable value of that part. A contractor or subcontractor who is not paid may suspend work without penalty after 7 calendar days’ written notice. Retainage is capped at 10% until the contract is 50% complete and 5% after that. A written contract can set its own payment terms where the statute allows. This is 815 ILCS 603/5, 603/10, 603/15, 603/20.

WhatIllinois
Payment deadlineOwner pays 15 days after approval; 10% a year interest
Who this coversPrivate construction, not only public works

What the statute says

“… the owner shall pay the amount due to the contractor pursuant to the payment application not more than 15 calendar days after the approval …”

Quoted word for word from the section’s text.

Source

815 ILCS 603/5, 603/10, 603/15, 603/20

Read the statute in the Illinois Compiled Statutes (Illinois General Assembly): ilga.gov.

Checked against the statute on November 15, 2026.

This is a summary of a published statute, not legal advice. Rules change, local ordinances can add to them, and the terms of a specific lease may differ. Check the citation and speak to a lawyer before acting.

How Seayora uses this rule

A contractor on Seayora keeps every job’s dates, its estimate, its invoices and its payments in one record, so the date work was last performed, the date each invoice went out and the amount still owed are on file when a lien or payment deadline is counted.

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