An unconditional lien waiver is a final release of lien rights for a specific amount or period that takes effect immediately on signing, regardless of whether the corresponding payment ever clears. If a contractor signs an unconditional waiver before the check actually clears the bank, and the check then bounces, lien rights are still gone. This is why unconditional waivers should never be signed in exchange for a check; they should be signed only after the funds have cleared.
Most states distinguish between progress and final unconditional waivers. The progress version releases lien rights for work performed through a specific date. The final version releases lien rights for the entire project, typically required at final payment. California, Texas, and Florida each publish or recognize specific statutory unconditional waiver forms; using the wrong form can void the waiver or create unintended consequences. The basic rule: conditional waiver in exchange for the check, unconditional waiver after funds clear.