CSI MasterFormat is a system developed and maintained by The Construction Specifications Institute (CSI) for organizing construction specifications into a standardized structure. It is used as part of the job costing process to efficiently manage the details of construction projects, including materials and labor costs associated with those projects. The system divides construction elements into 16 divisions, which are further broken down into individual sections. Each section contains its own detailed specifications, allowing contractors to quickly identify what materials they need to complete their work in compliance with project guidelines. CSI MasterFormat also aids in cost estimation and tracking expenses throughout the course of the project's development.

The latest version of CSI MasterFormat (2020 edition) was released in April 2020 and is the most up-to-date version available for use on residential construction projects. This version has been designed to reflect changes in the industry and provide even greater accuracy and detail when it comes to cost estimation, quality assurance, and material specification.