Cost vs Usage: When to Build a Cost Report That Doesn't Match Your Invoice

Cost vs usage is a critical concept in building cost reports for different departments, particularly in FinOps, where detective work is vital for understanding unexpected cost fluctuations. In a scenario where a company's engineering team saw a 20% cost increase without any product changes, the investigation revealed that the issue stemmed from a shift in Savings Plan coverage, favoring another team's new product and inadvertently increasing costs for the first team. This highlights the importance of tailoring cost reports to different needs; while finance departments benefit from reports that match invoice totals, engineering teams require reports that reflect cost changes resulting from their actions, filtering out external factors like discounts. Effective cost visibility programs should focus on providing meaningful and actionable insights to the relevant teams, ensuring clarity and accountability in managing cloud expenses.