Cost Codes and the CSI MasterFormat: A Construction Accounting Primer

Cost codes are the organizational backbone of construction accounting — the tags that turn millions of individual cost transactions into a coherent view of how a project is performing. The CSI MasterFormat is the industry-standard numbering system that most construction companies use as the foundation for their cost code structure. Here is how the system works, why the six-digit pattern matters, and how to set up a cost code structure that survives the life of a company.