Increase in Daily Azure Blob Storage and AFD Costs by 15-20% After Migrating from Legacy Billing to Modern Billing

We migrated from the Azure Legacy Billing platform to the Modern Billing platform on August 26, 2026. Since the migration, we have observed a 15–20% increase in our daily Storage and CDN costs across our Azure resources.

We have reviewed our resource usage and consumption metrics and have also confirmed with the Microsoft Support team that there has been no corresponding increase in our actual usage.

However, despite usage remaining consistent, the daily costs for Azure Storage and CDN have increased significantly after the billing platform migration.

We would like to understand whether this increase could be related to the migration to Modern Billing, specifically:

Were there any changes to billing meters, pricing, metering, or cost calculation as part of the migration?

Could Modern Billing calculate or report Storage and CDN costs differently from the Legacy Billing platform?

Are there any changes in how data transfer, storage transactions, CDN traffic, or other related charges are being aggregated or reported?

• How can we reconcile the costs before and after August 26, 2026 to identify the exact source of the increase?

Is there a recommended Azure Cost Management report or detailed billing dataset that we can use to compare the Legacy vs. Modern Billing charges?

Since the increase is not explained by a corresponding increase in resource usage, we would appreciate guidance from Microsoft or the Azure community on how to investigate this discrepancy and determine whether it is related to the billing platform migration.

We can provide Cost Management exports, meter details, usage metrics, and before/after cost comparisons if required.