cloudcostdown.euAWS Multi-Account · Cost Management Guide
AWS Multi-Account Cost Management: Organizations & Consolidated Billing
Series B–C companies typically run 5–20 AWS accounts. Consolidated billing shares volume discounts, Savings Plans apply across all accounts, but visibility and governance become harder without a structured approach.
Multi-Account Cost Management Practices
Use consolidated billing to maximize volume discounts
- Ensure all AWS accounts are under one AWS Organization
- Enable consolidated billing in the management account
- Savings Plans purchased in any account apply to all - buy from the management account for simplest visibility
- Reserved Instances share across the organization by default - verify in Billing preferences
Set up cross-account cost visibility
- Enable Cost Explorer in the management account - it shows all linked accounts
- Activate cost allocation tags in the management account - they apply to all accounts
- Create Cost Categories to group by account type (prod/staging/dev)
- Use AWS Cost and Usage Report (CUR) for programmatic access to detailed billing data
Enforce governance with Service Control Policies
- Restrict resource creation to approved regions: Deny if aws:RequestedRegion not in [eu-central-1, us-east-1]
- Require tags on resource creation: Deny CreateTags if missing required tags
- Prevent large instance types in dev accounts: Deny RunInstances if instance type is p3/p4/g4
- Block expensive services in development: Deny SageMaker:CreateEndpoint in dev OUs
Allocate shared service costs
- Shared services account costs (monitoring, DNS, CI/CD) need an allocation policy
- Option 1: Platform team absorbs all shared costs
- Option 2: Split proportionally based on each team's relative production spend
- Use AWS Cost Categories to automate cross-account cost allocation in reports
Frequently Asked Questions
Does AWS consolidate costs across multiple accounts?
Yes. AWS Organizations with consolidated billing combines usage across all linked accounts for volume discount purposes. Savings Plans and Reserved Instances purchased in any account apply to matching usage across all linked accounts. This means the more accounts you have under one organization, the better your volume pricing.
How do I see costs per AWS account?
Cost Explorer → Group by: Linked Account. This shows spend per account for the selected time period. In the management account, you can see all linked accounts. Individual accounts can only see their own costs unless they're granted access to the management account's Cost Explorer.
Do Savings Plans apply across AWS accounts?
Yes. Savings Plans purchased in any account in an AWS Organization apply to matching compute usage across all linked accounts in the organization. The management account can control whether Savings Plans discount sharing is enabled - it's on by default.
How should I structure AWS accounts for a startup?
Recommended minimum: Management account (billing only, no workloads), Shared Services account (CI/CD, monitoring, DNS), Production account, Staging account, and Development account. This provides cost isolation per environment and security boundaries between production and non-production. Use AWS Control Tower for automated account creation and governance.
What are Service Control Policies (SCPs) for cost management?
SCPs are guardrails applied at the AWS Organization level that restrict what IAM users and roles can do in member accounts - even root users. For cost management: SCPs can prevent resource creation in expensive regions, require tags on all resources, limit instance sizes, or block expensive service categories. They're the most powerful cost governance mechanism in AWS.