Cost Allocation Rules

How resource cost becomes application and workload cost.

Allocation links native AWS cost facts to business context. It is designed to be explainable and conservative: if no defensible rule assigns a cost, that amount stays UNALLOCATED.

Allocation precedence

The documented precedence is fixed:

Manual financial rule.
Direct resource/workload assignment.
Approved tag rule.
Measured usage where an actual data source is configured.
Configured percentage split.
Explicit equal split where policy permits it.
UNALLOCATED.

Note

The presence of a precedence position does not mean every method is operational. In particular, measured-usage attribution is not assumed to have a live source in the original v1 baseline.

Immutable runs

Allocation results are versioned. A successfully published run forms the authoritative historical financial view for its period; later tag edits, organization changes or rules do not silently rewrite that view. Recalculation must be represented by a new controlled run with lineage.

Financial controls

Percent splits should reconcile exactly in the recorded currency. An adjustment without a justified mapping remains at its proper account or organization level. When resource metadata is incomplete, use the unmapped-resource queue rather than hiding the gap.

Operating practice

Review the unallocated amount each cycle; fix high-impact owner/resource mappings first; keep historical and current assignments distinct; then re-run allocation and inspect the authoritative version. A lower unallocated share is useful only if achieved without inventing attribution.