What’s the best way to investigate unexpected Azure cost increases?

Good tagging is essential. Apply consistent tags for projects, owners, environments, and cost centers so that a spike can be traced back to the right workload. For resources that are particularly prone to sudden increases, create more focused baselines and alerts instead of relying only on an overall subscription budget.

Set budgets and alerts at the subscription level, then use historical spending to establish a realistic baseline. Azure’s anomaly alerts can help flag unusual changes, while regular reviews of costs by subscription, resource group, service, and tag help narrow down the source.

For larger environments, FinOps dashboards can provide a more centralized view across subscriptions and resource groups. The Azure FinOps Toolkit and its Power BI reports are useful starting points and can be customized. Some third-party tools also compare environment snapshots over time, linking cost anomalies to changes such as new resources, resized services, or configuration updates.

A practical approach is to export billing data from every subscription on a daily basis into a data lake or central storage account. From there, build a reporting dashboard that shows totals, detailed resource breakdowns, trends, and comparisons with the previous month. Reviewing it weekly makes it easier to spot changes and decide whether they are justified by increased usage or need corrective action.