Notify the agency and subcontractor, in writing, of his intention to withhold all or a part of the subcontractor's payment with the reason for nonpayment. 4.2 Time Extensions.A free, downloadable contract template. We'll help you create a good contract that protects your work and sets clear expectations for every project. Under the new statutory regime, contractors must pay subcontractors regardless of whether the owner has timely made payment to them.