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

Short description

RIs aren't physical instances. Instead, RIs are a billing discount that's applied to On-Demand Instances in your account.

If you purchased an RI and don't see the expected billing benefits, then it might be because of one of the following reasons:

• The payment for your RI wasn't successful.
• 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

The upfront cost for your RI must successfully process

When an RI payment fails, the RI status changes to payment-failed. Check the status of your payments on the Payment History page of the AWS Billing and Cost Management console. If an RI failed, then don't retry the payment. By the end of the month, the invoice is cancelled on your console. After the status changes to payment-failed, update the payment method in the account and purchase the RI.

To purchase an RI, see the following AWS documentation:

• Buy Reserved Instances for Amazon EC2
• Purchasing Reserved DB Instances for Amazon RDS
• Purchasing a reserved node (Amazon ElastiCache)

Your RI must be active

When you purchase an RI, you choose a 1-year or 3-year term. After the term expires, your instance is billed at the On-Demand Instance price. To continue to receive the discount, purchase another RI with the same specifications. To check if your RIs are active, open the Amazon EC2 console, and then choose Reserved Instances on the navigation pane.

Note: To avoid gaps in RI discounts, use reservation expiration alerts.

Your RI must match the On-Demand instance's attributes

Amazon EC2 RI

An Amazon Elastic Compute Cloud (Amazon EC2) RI must match an On-Demand Instance's type, Availability Zone, platform, and tenancy.

To view the attributes of your On-Demand Instance, complete the following steps:

1. Open the Amazon EC2 console.
2. On the navigation pane, choose Running instances, and then select the running On-Demand Instance.
3. On the navigation pane, choose Reserved Instances, and then select the RI.
4. Check whether the RI was launched with the same attributes as the On-Demand Instance.

To check if you're fully using your EC2 RIs, see How do I find out if my Amazon EC2 Reserved Instances are being fully used?

Amazon RDS RI

If you use an Amazon Relational Database (Amazon RDS) RI, then the RI must 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.

For a reserved DB instance, you receive a discount only for the instance usage. You don't receive a discount for costs that are associated with storage, backups, and I/O. For more information, see Reserved DB instance billing example.

Note: After you purchase a DB RI, you can't change the AWS Region, DB engine, DB instance class, offering type, and term.

OpenSearch Service RI

For RIs in 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.

ElastiCache Reserved Nodes

If you use an ElastiCache reserved node, then the specifications of the reserved node must match the specifications of the On-Demand node. Otherwise, the node is billed at the On-Demand rate.

Each hour, the number of running cache nodes is assessed. If the number is less than or equal to your reserved cache nodes, then you are charged at the reserved cache node hourly rate. If the number of running cache nodes exceeds the number of applicable reserved cache nodes, then you're charged the On-Demand rate.

Capacity Reservations

If you created an On-Demand Capacity Reservation, then the Capacity Reservation remains unused until you run an EC2 instance with matching attributes. If you don't run an instance with matching attributes, then the Capacity Reservation appears as unused on your EC2 bill.

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

You must have one RI for each instance

You must have one RI for each instance that you want to receive a discount. All additional running instances are billed at the On-Demand Instance price. RI billing benefits apply only to one instance-hour at each clock-hour.

Determine whether your RI is size flexible or has a Regional benefit

Check if your RIs are size flexible or have 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 all or part of its pricing benefit to any On-Demand Instance in the same instance family. The Availability Zone or instance size doesn't matter. For more information, see How do I find out if my Amazon EC2 Reserved Instance provides Regional benefits or size flexibility?

Related information

How billing works with Reserved Instances

Examples of applying Reserved Instances

How do Amazon EC2 Reserved Instances that are size-flexible apply to my AWS bill?