Microsoft make changes to when customers are invoiced for overage on their Azure Monetary Commitment. Historically, this has been quarterly or annually, dependent on agreement type, which was changed to quarterly for all customer and agreement types in December 2017. Now all overage will be charged at the end of each month.
See page 50 of the May 2018 Product Terms for the official wording.
There are two changes to the way Azure Monetary Commitment works in an Enterprise Agreement from December 2017.
Historically, Monetary Commitment was an amount paid upfront annually for the Azure consumption services which was decremented as services were used, with any unused Monetary Commitment being forfeited at the end of the year. This remains as an “Annually Prepaid Option” but now there’s a “Fully Prepaid Option” too. Under this option a customer pays for 36 months of Monetary Commitment upfront but the funds are available for the whole of the Enrolment term. This means there are also some changes in the minimum amount of Monetary Commitment required: $3,600 under the Enterprise Enrolment and $36,000 under the Server and Cloud Enrolment.
The second change is the removal of the Consumption Allowance: previously customers with a Direct EA could pay for any Azure overage at anniversary if they remained within the Consumption Allowance (50% of the original Monetary Commitment). Now all new and renewing EA customers will pay for overage on a quarterly basis.
If you want the official wording on the new rules then it’s all on pages 50 and 51 of the December 2017 Product Terms document.