Unfortunately for Illinois construction participants, the law surrounding popular contingent payment provisions, such as pay when paid and pay if paid clauses, is cloudy. We underscored this fact in the article “What Happens When Pay If Paid Clauses Are Disallowed, But Not Entirely.”
770 Ill. Comp. Stat. 60/21 provides that conditional payment provisions, like pay if paid and pay when paid clauses, “shall not be a defense by the party responsible for payment to a [mechanics lien] claim.”  Accordingly, these clauses will not prohibit a party from filing a mechanics lien claim. However, it is unclear as to whether the clauses could be used by a party in defense to a contractual claim for payment.  The clause, in other words, is only conditionally unenforceable and not completely void on its face.
While this is highly suggestive that the clause would be considered void or very strictly construed by an Illinois court, there is still a little sign of life in the provision.