Conditional waivers are used before payment has been received, and unconditional waivers are used after payment is made. As the name implies, a conditional waiver means signing the waiver is a “condition” of the contractor receiving payment. However, until they receive payment, they are within their rights to file a lien.
Unconditional waivers take effect immediately upon being signed, regardless of whether or not the contractor was paid. It is for this reason it is important for contractors to hold off on signing an unconditional waiver until they receive compensation for their services.