Why isn't my Reserved Instance applying to my AWS billing?

Last updated: 2022-03-08

I purchased a Reserved Instance (RI), but I'm not getting a discount.

Short description

You purchased an RI, but aren't seeing the expected billing benefits due to one of the following reasons:

  • The payment for your RI was unsuccessful.
  • Your RI isn't active.
  • Your RI doesn't match the specifications of running instances.
  • Your RI is size-flexible, or has the Regional benefit, and the benefit is applying to a different On-Demand Instance.

Resolution

RIs aren't physical instances. Instead, they are a billing discount applied to On-Demand Instances in your account. For an RI's discount to apply, the following conditions must be true:

  • The upfront cost for your RI must process successfully. Check the status of your payments on the Payment History page of the Billing and Cost Management console. To retry a failed RI payment, contact AWS Support. Failed RI purchases from previous billing periods can’t be retried.
  • Your RI must still be active. When you purchase an RI, you choose a one-year or three-year term. After the term expires, your instance is billed at the On-Demand Instance price. To continue receiving the discount, purchase another RI with the same specifications. To check if your RIs are active, you can sign in to the Amazon EC2 console, and then choose Reserved Instances from the navigation pane.
    Tip: To avoid gaps in RI discounts, use reservation expiration alerts.
  • If you have an Amazon Elastic Compute Cloud (Amazon EC2) RI, the RI must exactly match a running EC2 instance’s characteristics. To get the maximum benefit from your RI, a running On-Demand Instance must exactly match the instance type, Availability Zone, platform, and tenancy of your RI. To review the characteristics of your running EC2 instance, sign in to the Amazon EC2 console, choose Running instances, and choose the running On-Demand Instance. Then, choose Reserved Instances from the navigation pane, and check if the RI was launched with similar attributes. To check if your EC2 RIs are being fully used, see How do I find out if my Amazon EC2 Reserved Instances are being fully used?
  • If you have an Amazon Relational Database (Amazon RDS) RI, the RI must exactly match the specifications of a running DB instance. Otherwise, the DB instance is billed at the On-Demand rate. For more information, see Amazon RDS Reserved Instances. The charges for a reserved DB instance cover only the instance costs. These charges don't include regular costs associated with storage, backups, and I/O. For more information, see Reserved DB instance billing example. Note that the Region, DB engine, DB instance class, Offering type and Term chosen during the purchase of RI can't be changed later.
  • If you have Reserved Instances in Amazon OpenSearch Service, the RI must match the Region, instance class, and instance type of the standard On-Demand Instance. Otherwise, the instance is billed at the On-Demand rate.
  • If you have an Amazon ElastiCache Reserved Node, the specifications of the Reserved Node must match those of the On-Demand node. Otherwise, the node is billed at the On-Demand rate. Each hour, if the number of running cache nodes is less than or equal to the number of applicable Reserved Cache Nodes you have, all running cache nodes are charged at the Reserved Cache Node hourly rate. If the number of running cache nodes exceeds the number of applicable Reserved Cache Nodes, you are charged the On-Demand rate.
  • You must have one RI for each instance that you want to receive a discount. Each RI provides the discount to only one running EC2 instance at a time. All additional running instances are billed at the On-Demand Instance price. RI billing benefits apply only to one instance-hour per clock-hour.
  • Your RI is applying to a different instance. Check if your RIs are size-flexible or has the Regional benefit. An RI with the Regional benefit applies to any On-Demand Instance in the same Region with matching specifications. An RI that's size-flexible applies either all or part of its pricing benefit to any On-Demand Instance in the same instance family, irrespective of the Availability Zone or instance size. For more information, see How can I find out if my Amazon EC2 Reserved Instance provides regional benefit or size flexibility?
  • If you purchased an On-Demand Capacity Reservation, it remains unused until an EC2 instance with matching attributes is running. If an EC2 instance with matching attributes isn't running, then the capacity reservation will appear as an unused reservation on your EC2 bill. To check if your EC2 RIs are being fully used, see How do I find out if my Amazon EC2 Reserved Instances are being fully used?

If your RI is active and matches the specifications of a running On-Demand Instance, use Cost Explorer to analyze your spending and usage. You can use AWS Cost Explorer to generate the RI Utilization and RI coverage reports. For more information, see How do I view my Reserved Instance utilization and coverage?