This document explains how Cloud de Confiance by S3NS shares resource-based committed use discounts (CUDs) across projects in your Cloud Billing account.
CUD sharing pools your resource-based committed use discounts (CUDs) at the Cloud Billing account level so that a commitment purchased in one project can cover eligible resource usage in any other project linked to the same account. With CUD sharing enabled, you maximize your savings and reduce the overhead of managing discounts on a per-project basis.
How CUD sharing works
CUD sharing is the default operating model for most Cloud Billing accounts. When CUD sharing is enabled, Cloud de Confiance automatically aggregates CUDs from all active resource-based commitments within a Cloud Billing account and applies the resulting discounts to eligible resource usage across all associated projects.
For example, you purchase two resource-based commitments for 80 vCPUs each
(a total of 160 vCPUs) in Project A, but your total monthly usage reaches
200 vCPUs. Suppose that these 200 vCPUs are distributed across multiple projects
in your Cloud Billing account. Because CUD sharing is enabled for the
account, you receive the applicable resource-based CUDs for 160 of those
200 vCPUs, regardless of which projects run the compute instances. The
additional 40 vCPUs are billed at standard on-demand rates. If you prefer to
keep a project's CUDs strictly isolated to the purchasing project, then you can
disable CUD sharing for your Cloud Billing account at any time.
CUD scope and default configuration
You enable or disable CUD sharing by changing the CUD scope in your Cloud Billing account. Resource-based CUDs have two scope options:
- Project: Resource-based CUDs from a commitment apply only within the project in which you purchased the commitment.
- Billing account: Resource-based CUDs from commitments apply across all projects linked to the Cloud Billing account.
The default CUD scope for all new billing accounts is Billing account (CUD sharing enabled). On June 16, 2026, the default CUD scope changed from Project to Billing account for most billing accounts. To prevent any disruption to your active billing configurations with this change, Cloud de Confiance by S3NS auto-configured your Cloud Billing account's CUD scope in the following way, depending on the account's creation date and the active commitments:
- Cloud Billing accounts created on or after June 16, 2026: The scope is Billing account (CUD sharing enabled) by default.
- Cloud Billing accounts created before June 16, 2026:
- If the Cloud Billing account had no active resource-based commitments on June 16, 2026, then the CUD scope was changed to Billing account (CUD sharing enabled) on that date.
- If the Cloud Billing account had any active resource-based commitments on June 16, 2026, then Cloud de Confiance preserved the existing CUD scope (either Project or Billing account) that was in place on that date.
You can manually enable or disable CUD sharing at any time by changing your CUD scope configuration. For instructions, see Enable CUD sharing or Disable CUD sharing.
After you change your CUD scope, the time it takes for the change to take effect depends on your selection:
- Billing account (enabling CUD sharing): The change takes effect at 12:00 AM US and Canadian Pacific Time the following day.
- Project (disabling CUD sharing): The change takes effect within a few moments.
Attribution for shared CUDs
Attribution refers to how Cloud de Confiance allocates your CUDs across projects when CUD sharing is enabled. These allocations are reflected in Cloud Billing cost management interfaces, such as the usage cost export or the Cloud de Confiance console.
For resource-based CUDs only, you can choose one of the following types of attribution:
- Proportional attribution. Your CUDs are shared across projects based on each project's proportion of the total eligible usage. This is the default attribution type.
- Prioritized attribution. You specify the order in which projects receive CUDs.
Proportionally attributed commitments are applied to usage from projects
based on each project's share of the total eligible usage. For example, suppose
project A consumes US$75 worth of usage and project B consumes US$25 worth
of usage, then project A gets covered by up to 75% of the available CUDs and
project B gets covered by up to 25%.
Prioritized attribution applies your commitments to usage based on the distribution settings that you specify. You can choose the projects, along with the amount of usage within each project, that get covered by the commitments. After your prioritized commitments are applied to eligible usage, any remaining unprioritized commitments are applied proportionally to the eligible usage in your remaining projects. The total amount of the allotments cannot exceed the commitment amount purchased.
You can update attribution preferences anytime during the commitment's lifetime. However, any attribution preferences that you configure are applied only if CUD sharing is enabled. To choose proportional or prioritized attribution for your Compute Engine commitments, see choose attribution for resource-based commitments.
Impact of changing a project's Cloud Billing account
If you move the project that is associated with a commitment to a different Cloud Billing account, then you continue to receive CUDs under the destination Cloud Billing account for the commitments associated with that project. However, the source account's attribution and CUD sharing settings no longer apply to the project. Instead, the project inherits the attribution and CUD sharing settings that apply to the destination account.
For example, suppose that you have CUD sharing enabled in the source account and disabled in the destination account. After you move your project, the projects in the source account no longer receive CUDs from resource-based commitments that are tied to the moved project. In the destination account, because CUD sharing is disabled, the resource-based CUDs are limited to the moved project.
For more information about changing the Cloud Billing account for a project, see Change the billing account for a project.
Limitations
If you have a shared reservation in a project and want usage from the shared projects to be eligible for shared CUDs from your commitment's Cloud Billing account, then you must share your reservation only with projects that are linked to the same Cloud Billing account. Otherwise, usage from those projects won't be eligible for shared CUDs and you might be charged the on-demand rates.
When CUD sharing is enabled for a Cloud Billing account, if any portion of a commitment remains unutilized within a given month, then the commitment fee for that remaining portion gets charged to the project where you purchased that commitment.
Check whether CUD sharing is enabled
To check if CUD sharing is enabled for your Cloud Billing account, complete the following steps:
In the Cloud de Confiance console, go to the CUD analysis page.
At the prompt, choose the Cloud Billing account that you want to view. The Committed use discount analysis page appears.
In the Analyze menu, select Resource-based CUDs. The CUD scope & settings button appears in the toolbar.
Click CUD scope & settings.
In the Resource-based CUDs scope section of the CUD scope & settings page that appears, you can review your current CUD scope configuration. The CUD scope can be one of the following:
Project: This selection indicates that CUD sharing isn't enabled for resource-based commitments. CUDs from a commitment apply to eligible usage only in the project where the commitment was purchased.
Billing account: This selection indicates that CUD sharing is enabled for resource-based commitments. CUDs from any resource-based commitment in the current Cloud Billing account are shared and applied to eligible usage across all projects that are associated with the Cloud Billing account.
Enable CUD sharing
If CUD sharing isn't enabled on your Cloud Billing account, then you can enable CUD sharing by changing the CUD scope to Billing account in the Cloud de Confiance console. After you change your CUD scope to Billing account, CUD sharing is enabled on all of the current and future projects that are associated with the Cloud Billing account.
CUD sharing works in conjunction with your attribution configuration. When CUD sharing is enabled, it defaults to using proportional attribution for your Compute Engine resource-based commitments. If CUD sharing is disabled on your Cloud Billing account and you plan to configure prioritized attribution, then Google recommends that you configure the prioritized attribution settings in the Cloud de Confiance console before you enable CUD sharing. For more information, see CUD sharing best practice for prioritized attribution.
To enable CUD sharing, complete the following steps:
In the Cloud de Confiance console, go to the CUD analysis page.
At the prompt, choose the Cloud Billing account for which you want to enable CUD sharing.
In the toolbar of the CUD analysis page, click CUD scope & settings. The CUD scope & settings page appears.
In the Resource-based CUDs scope section, select Billing account.
To save your updated CUD scope and enable CUD sharing, click Save.
After you save the changes, the updated CUD scope takes effect at 12:00 AM US and Canadian Pacific Time the following day. You can verify that the CUD scope is correctly set.
Disable CUD sharing
To disable CUD sharing, complete the following steps:
In the Cloud de Confiance console, go to the CUD analysis page.
At the prompt, choose the Cloud Billing account for which you want to disable CUD sharing.
In the toolbar of the CUD analysis page, click CUD scope & settings. The CUD scope & settings page appears.
In the Resource-based CUDs scope section, select Project.
To save your updated CUD scope and disable CUD sharing, click Save.
After you save the changes, the updated CUD scope takes effect within a few moments. You can verify that the CUD scope is correctly set.
What's next
- Learn about attribution for resource-based commitments.
- Learn how to analyze the effectiveness of your CUDs.