palaniappan p7 min
AWS Tagging, Chargeback, and FinOps Ownership (2026): Tag Policy vs SCP, the Untaggable 21%, and Splitting Shared Cost Without a Spreadsheet War
Tag policies report; only an SCP prevents untagged spend. And ~21% of a typical bill — egress, inter-AZ transfer, Enterprise Support, shared platform services — carries no tag any tool can read. Here is the two-layer enforcement model, the Cost Categories split-charge rules that replace the monthly allocation spreadsheet, and why you show back before you charge back.