National Association of Credit Management

Under Maryland law, there is no public policy against an advance waiver of the right to file a Mechanic's Lien by the contractor in the construction contract with the owner.
An owner or contractor cannot by any term of the prime contract, waive or impair the lien rights of others.
Subcontractors and suppliers may not waive their lien rights on in construction contracts between the contractor and subcontractor.
Further, a pay-if-paid clause does not waive lien rights.
"Paid if Paid" is enforced if explicit.
"Pay when Paid" suggests time for payment.
Pay-when-paid clause in the subcontract or purchase order does not create a condition precedent to payment.