Which action should the company take to accomplish this goal with the LEAST operational overhead?
Add a department tag to each resource and configure cost allocation tags.
Move each department resource to its own VPC.
Move each department resource to its own AWS account.
Use AWS Organizations to get a billing report for each department.
Explanations:
Adding a department tag to each resource and configuring cost allocation tags allows the company to track resource usage per department within the same VPC. This method requires minimal operational overhead since it leverages existing tagging capabilities in AWS and provides detailed billing reports by department.
Moving each department resource to its own VPC increases operational overhead significantly. Each VPC would require its own management, security configuration, and potentially additional costs, complicating the billing process rather than simplifying it.
Moving each department resource to its own AWS account provides clear billing separation but results in high operational overhead. Managing multiple accounts adds complexity, and the cost of inter-account data transfer can be significant.
Using AWS Organizations for billing reports can provide visibility across accounts, but it requires each department to be in separate accounts, increasing operational overhead and complexity. It does not address the single VPC requirement effectively.
I structure that the answer is:
Add a department tag to each resource and configure cost allocation tags.