agent applied cost allocation tags to snapshots, the tags propagated and doubled the attribution

TL;DR

Cost allocation tags on snapshots re-attribute snapshot spend on top of the volume spend they derive from, which doubles the numbers in allocation reports. Do not put cost-center allocation tags on snapshots; if they are already there, remove them or exclude snapshot line items from the allocation views.

agent applied cost allocation tags to snapshots, the tags propagated and doubled the attribution

Use this when

• Cost allocation reports show inflated or doubled spend for tagged teams.
• Snapshots carry the same cost-center tags as their source volumes.
• An agent applied allocation tags broadly, including to snapshot resources.

Not for this skill when

• The tags are operational (owner, retention date) rather than cost allocation tags. Those are harmless on snapshots.
• Your allocation reports already exclude snapshot line items. The tags are then inert.

Steps

1. Confirm the doubling: compare the allocation report total against the actual CUR total. Verify: the allocated sum exceeds the real spend.
2. List snapshots carrying cost allocation tag keys: filter by the tag keys your org activates for allocation.
3. Remove the allocation tags from the snapshots (keep operational tags like retention or owner).
4. Alternatively, exclude the snapshot usage type from the allocation report views if the business wants the tags to stay for other reasons.
5. Fix the tagging automation: exclude snapshot resource types from allocation-tag application.
6. Re-run the allocation report and verify the totals reconcile with the CUR.

Variant phrasings

cost allocation tags snapshots double counting

The accounting phrasing.

ebs snapshot tags inflated cost report

Symptom-level search.

exclude snapshots from cost allocation

The fix framing.

Compatibility: AWS cost allocation tags; EBS snapshots inherit or receive tags via automation or copy-tags settings.

Why it happens

Allocation tags are meant to answer "who pays for this resource." A snapshot is a derivative of a volume whose cost is already allocated, so tagging the snapshot allocates the same dollars twice. The automation applied a sensible rule (tag everything with the cost center) to a resource type where the rule does not hold.

Edge cases / pitfalls

• Copy-tags-from-volume settings propagate allocation tags to snapshots automatically; check the volume and snapshot copy settings, not just the automation.
• AMI deregistration does not delete snapshots; orphaned snapshots with allocation tags keep polluting reports until removed.
• Some teams want snapshot costs visible per team. Give them a separate snapshot-only view instead of allocation tags.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_jfY9abuHYxaLb566pa2TVg