Cosmos db - Inter Region Data Transfer Out Charges (Even with same region)

Mathew James 421 Reputation points
2026-09-29T04:35:53.72+00:00

I do have a Cosmos db in Provisioned throughput mode and opted under Free tier total RU/s is put as 1000 max as Shared database throughput and which is in South India Region. All my other applications like Azure function apps are also in South India. Still I keep getting this charge

Inter Region Data Transfer Out - Close to Rs 1000 (Indian Rs).

I have a raised a ticket to Microsoft and no reply for several Months. can anyone help me here. How to figure this out like why this charge is coming up.

What I have also done is setting up the region as South India in the code when I create the cosmos connection in the connection builder. Still no luck. I just need to figure out from where these charges are coming up.

Appreciate your help....

Cosmos Charges.jpgRegards
-Mathew James

Azure Cosmos DB
Azure Cosmos DB

An Azure NoSQL database service for app development.

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  1. Mathew James 421 Reputation points
    2026-09-29T05:13:50.1566667+00:00

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  2. SHOUMIK CHAKRAVARTY 910 Reputation points
    2026-09-29T05:02:35.3133333+00:00

    Hello @Mathew James - Free tier isn't a blanket exemption. Per the free tier documentation, "you get the first 1000 RU/s and 25 GB of storage in the account for free. The throughput and storage consumed beyond these limits are billed at regular price. It covers throughput and storage so a data transfer charge on a free tier account is expected rather than a billing error.

    As for why anything leaves South India when all your resources are there, backups do it by default. From Periodic backup storage redundancy:

    "By default, Azure Cosmos DB stores periodic mode backup data in geo-redundant Azure Blob Storage. The blob storage is then, by default, replicated to a paired region."

    The backup introduction describes the same mechanism and links the region pairs list. It happens regardless of your account region, your functions, or your connection settings, which is why none of your changes helped.

    Microsoft's own best practice is to turn it off:

    "Change the default geo-redundant backup storage to ensure that your backup data stays within the same region where your Azure Cosmos DB account is provisioned. You can configure the geo-redundant backup to use either locally redundant or zone-redundant storage."

    Change it with Azure PowerShell or the Azure CLI, or enforce it with Azure Policy across accounts.

    No doc connects this directly to the Inter Region Data Transfer Out line, so I can't say that's your charge. It is the only thing in your setup moving data across regions though, and changing it is free, so it's worth trying and seeing what next month's bill looks like.

    Help make this community better for everyone: if this answer resolved your issue, please accept it or leave an upvote. If not, share more details in a comment so we can continue the discussion and find the right solution.

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