AWS Cost and Usage Reports (CUR) with the "Overwrite Existing Report" option and Report data time granularity "Daily"

Thank you for your question about AWS Cost and Usage Reports (CUR) with the "Overwrite Existing Report" option and "Daily" granularity. Let me address your concerns:

Finalization of the prior month's folder: The prior month's folder typically gets finalized after AWS issues the invoice for that month, which usually occurs within the first few days of the following month.

Determining if the prior folder is finalized: You can check if a report is finalized by looking at the "bill/InvoiceId" column in the report. If this column is populated with an invoice ID, it indicates that the line item or the entire report is final. If it's blank, the report is not yet finalized.

Maximum time for prior month folder finalization: While the exact timing can vary, AWS generally finalizes the prior month's report within the first week of the new month. However, it's important to note that even after finalization, AWS might update the report if they apply refunds, credits, or support fees to your usage for the month.

Additional considerations: AWS updates Cost and Usage Reports at least once a day until charges are finalized. After finalization, updates for refunds, credits, or support fees are typically reflected by the 6th or 7th of the month for the prior month's report. With the "Overwrite Existing Report" option, each update overwrites the previous version, so you'll always have the most current data in your specified S3 location.

Hopefully this helps provide some clarification on your question. If you still have questions, I'd recommend opening an AWS Support case with the Billing Team https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/billing-get-answers.html#:~:text=Sign%20in%20and%20navigate%20to,required%20fields%20on%20the%20form..

Thank you for using AWS!

Brian