Missing Shared Scope Configuration for Azure Reservations

Explanation

When reservations are scoped only to a single subscription, any unused capacity cannot be applied to matching resources in other subscriptions within the same tenant. This leads to underutilization of the committed reservation and continued on-demand charges in other parts of the organization. Enabling Shared scope allows all eligible subscriptions to consume the reservation benefit, improving utilization and reducing overall spend. This is particularly impactful in environments with decentralized provisioning, such as across dev/test/prod subscriptions or multiple business units.

Relevant Billing Model

Prepaid commitment for reserved capacity (hourly usage covered by reservation, regardless of whether resource is provisioned)

Detection

• Check for reservations that consistently show low utilization over a representative time window
• Evaluate whether matching on-demand resources exist in other subscriptions within the same tenant
• Assess whether the reservation scope is currently set to 'Single' rather than 'Shared'
• Determine if usage patterns across subscriptions are dynamic or uneven, which would benefit from shared scope flexibility

Remediation

• Change reservation scope from *Single* to *Shared* in the Azure Portal or via API
• Reevaluate periodically to ensure the scope aligns with current organizational structure and usage distribution