Here in Arizona there is a process called certification and approval. For example, the carpentry contractor must turn in labor and material bills from mechanics and materialmen in order to be reimbursed for these costs. Progress payments are based on these bills. Once the property owner receives the labor and material bills they are considered certified and approved fourteen days after receipt of these bills unless there is a written objection. Payment must then be made within seven days after approval. The carpentry contractor cannot be reimbursed for these costs without furnishing these bills. So the carpentry contractor would need an invoice from the lumber yard for lumber, labor bills from persons, firms, or corporations who perform labor, and so forth.