Enable tag policies within the organization, create a tag policy for the BusinessUnit tag, ensure tag key capitalization compliance is disabled, apply the tag policy to ec2:instance resource types, and attach the tag policy to the organization's root.

Enable tag policies within the organization, create a tag policy for the BusinessUnit tag, ensure tag key capitalization compliance is enabled, apply the tag policy to ec2:instance resource types, and attach the tag policy to the organization's management account.

Create a Service Control Policy (SCP) and attach it to the organization's root, including a statement in the SCP to enforce tagging.

Create a Service Control Policy (SCP) and attach it to the organization's management account, including a statement in the SCP to enforce tagging.