Multi-Account AWS Cost Governance

Why Multi-Account Cost Governance Matters

As organizations grow on AWS, they adopt multi-account strategies for security, compliance, and blast-radius isolation. But without centralized cost governance, each account becomes a cost silo where spending goes unchecked.

Setting Up AWS Organizations for Cost

1. Consolidated Billing — All member accounts roll up to the management account. You get a single invoice and benefit from volume pricing tiers across the organization.
2. Cost Allocation Tags — Define organization-wide tagging standards. Use SCPs to enforce tagging on resource creation.
3. Linked Account Budgets — Create AWS Budgets per account or per tag, with alerts at 80% and 100% thresholds.

Service Control Policies (SCPs) for Cost

SCPs can prevent expensive actions organization-wide:

{
  "Version": "2012-10-17",
  "Statement": [{
    "Sid": "DenyExpensiveInstances",
    "Effect": "Deny",
    "Action": "ec2:RunInstances",
    "Resource": "arn:aws:ec2:*:*:instance/*",
    "Condition": {
      "ForAnyValue:StringNotLike": {
        "ec2:InstanceType": ["t3.*", "t3a.*", "m5.*", "m6i.*", "m6g.*", "c5.*", "c6i.*", "r5.*"]
      }
    }
  }]
}

FinOps Team Structure

For organizations spending over $50K/month on AWS, establish a FinOps practice:

• Weekly cost review — 30-minute meeting reviewing Cost Explorer dashboards
• Monthly optimization sprint — Dedicated time for right-sizing, cleanup, and commitment purchasing
• Quarterly architecture review — Evaluate workload placement and reserved capacity

Tools and Automation

• AWS Cost Anomaly Detection — ML-powered alerts for unusual spending
• AWS Budgets Actions — Automatically restrict actions when budgets are exceeded
• Cost and Usage Reports (CUR) — Export detailed billing data to S3 for custom analysis in Athena or QuickSight

Eazy SaaS Tip: Start with consolidated billing and organization-wide cost allocation tags. Then add per-account budgets and SCPs to prevent runaway costs. This three-step foundation covers 80% of cost governance needs.