Phase 1 – Pre-Closure Assessment & Planning

Goal: Confirm business need, identify cost and compliance impact before touching resources.

1. Inventory & Cost Review

• Generate a complete cross-region inventory with:
  • AWS Resource Explorer
  • aws resourcegroupstaggingapi get-resources
  • AWS Config and Trusted Advisor
• Review Cost Explorer → Last 3 months for anomalies.
• List active Reserved Instances (RIs), Savings Plans, and Marketplace subscriptions.
• Note any active Direct Connect, Dedicated Hosts, or Elastic IPs (common hidden cost centers).

2. Stakeholder & Compliance Approval

• Confirm with application, finance, and compliance owners that the account can be retired.
• Document decision in your Org change log / Confluence / ticket.
• Capture last backup requirement or legal retention if any.

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Phase 2 – Resource Cleanup (Recommended for Zero Residual Cost)

While AWS allows closure without cleanup, costs persist until resources are deleted or RIs expire.
Clean up to prevent hidden post-closure billing.

🔹 Critical Items

Category	Action
AWS Marketplace	Cancel every subscription in [Marketplace → Manage Subscriptions]. Terminate instances that used marketplace AMIs.
Reserved Instances & Savings Plans	These continue billing until expiry. Attempt transfer to another Org account via Support.
Data Backups	Export or snapshot any S3, RDS, EBS, ECR data you need. Then delete storage to stop meter accrual.
Direct Connect & Dedicated Resources	Explicitly delete DX connections, private virtual interfaces, and dedicated hosts to stop port-hour charges.
Other Persistent Costs	Release Elastic IPs, delete NAT Gateways (≈ $0.045/hr + data), and disable CloudWatch Logs retention if unneeded.

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Phase 3 – Account Closure Execution

You, as the Management Account Admin, can close member accounts in two AWS-supported ways:

Option 1 – Console

1. Sign in as Management Account → AWS Organizations
2. Choose the target member account
3. Click Close account → Confirm

Option 2 – CLI (CloudShell)

aws organizations close-account --account-id <member-account-id>
Code language: HTML, XML (xml)

AWS automatically:

• Revokes IAM access for that member
• Marks it CLOSED in Organizations
• Freezes new resource creation

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Phase 4 – Post-Closure Monitoring

Billing

• You remain liable for all usage until the closure timestamp.
• Final bill arrives the following month.
• RIs/SPs continue billing until expiry.
• Account remains visible as “CLOSED” for 90 days.

Recovery

• Within 90 days → Contact AWS Support → Reopen.
• After 90 days → Permanent deletion (no recovery).

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Phase 5 – Organization-Level Governance & Prevention

Control	Purpose
Service Control Policies (SCPs)	Block creation of cost-bearing resources in deprecated accounts or regions.
Budgets & Cost Anomaly Detection	Catch stray spend early.
AWS Config & CloudTrail (Org scope)	Track configuration and deletion compliance.
Automated Cleanup Scripts	Implement Lambda or Step Functions that auto-delete idle EBS, S3, EIPs.
Lifecycle OU Structure	Maintain “Active”, “Sandbox”, and “Decommissioned” OUs for clear separation.

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Recommended Timeline

Week	Tasks
Immediate	Audit account, identify Marketplace subs & DirectConnect links.
Week 1	Back up critical data, cancel Marketplace subs.
Week 2	Delete resources / release IPs / terminate NAT Gateways.
Week 3	Verify zero usage → Close account via Organizations.
Month After	Review final bill & ensure no unexpected charges.

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Common Hidden Costs to Double-Check

✅ NAT Gateways
✅ Elastic IPs (allocated but unused)
✅ CloudWatch Logs retention
✅ EBS Snapshots
✅ Direct Connect ports
✅ Active Savings Plans / RIs
✅ Marketplace licensing
✅ PrivateLink endpoints

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Official AWS References

• Close an AWS Account – AWS Account Management Docs
• Closing a Member Account in AWS Organizations
• Streamlining AWS Organizations Cleanup Strategies – AWS Cloud Ops Blog
• AWS re:Post – Decommissioning an Organization Account

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Final Action Plan (Summary)

1. Audit & Backup → Inventory, cancel Marketplace subs, note RIs/SPs.
2. Clean Up Resources → Terminate compute, delete storage, remove DX links.
3. Verify Zero Spend → Check Cost Explorer & Budgets.
4. Close Account via Organizations (console or CLI).
5. Monitor Final Bill & ensure RIs/SPs handled.
6. Apply Org-level SCPs & budgets to avoid future waste.

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