The insurance carrier for the Subcontractor must have an A.M Best Rating of A- or better and the rating must be listed in the Certificate of Insurance. How do I fill this out?To fill out this document, first gather all required information such as your company details and insurance information. Clark requires suppliers to receive Purchase Orders and submit Invoices electronically either via Coupa Supplier Portal (CSP) and cXML. Transmission. The subcontractor's guide to working with Clark Construction, including their history, how to prequalify, payment tips, and more. All trade contractors need to complete our Subcontractor Qualification Application to be eligible to bid on our projects and contract with Clark. When drafting a buyout agreement, you should be sure to address specifics pertaining to your business and what will happen upon the departure of an owner. When creating the Purchase Order, follow the instructions in Smart Buy Plus and attach a copy of the signed contract. Step 5: Submit for Payment.