FinOps

Q) What is the difference between Actual Cost and Amortized Cost?

Consider a platform team managing a hub-and-spoke landing zone setup under a central billing account. To optimize compute spend, the team purchases a 3-year Azure Compute Savings Plan upfront for $36,000, which applies globally across multiple application landing zone subscriptions, such as sub-app-prod-001 and sub-app-dev-001.

Under Actual Cost, the entire $36,000 invoice charge is logged on Day 1 against the central management subscription where the savings plan was purchased. In Month 1, the central platform team’s budget shows a massive $36,000 spike, while Months 2 through 36 show $0. Meanwhile, sub-app-prod-001 and sub-app-dev-001 consume compute hours throughout the year without reflecting any share of that upfront commitment on their monthly invoices, making workload teams appear artificiality cheap to run.

Under Amortized Cost, Azure Cost Management breaks down the $36,000 upfront purchase into $1,000 per month ($33.33 per day) and redistributes that cost directly to the individual landing zone subscriptions based on their actual hourly compute consumption. If sub-app-prod-001 consumed 70% of the discounted compute hours in a month and sub-app-dev-001 consumed 30%, amortized reporting allocates $700 to the production landing zone and $300 to the dev landing zone.

Actual cost is used by finance for cash-flow management and paying the monthly Microsoft invoice. Amortized cost is used by cloud engineers and FinOps teams to establish accurate unit economics, track real subscription consumption, and fairly attribute shared commitment discounts across landing zones.