Below is a template for an interior design services contract. This page provides access to the majority of standard templates related to contracting.What should be included in an interior design contract? How do I fill this out? Upon written approval of RECS PM, fill out a Supplemental Agreement Construction Contracts form (S. A.), and attach cost breakdown. Use this interior design contract template as a binding agreement for clients for your interior design services. Interior Design Services Contract : Utilize our Interior Design Services Contract for a legally binding agreement between an interior designer and a client.