Keep shared Azure cost allocation separate from billing
On this page
Keep allocation results out of invoice reconciliation: use them for internal chargeback, then check each rule's source, targets and split. Skipping this can assign reported costs to the wrong team without changing who owes Azure.
What you need first
- Tool
- Microsoft Cost Management is Azure's cost reporting tool. For a targeted resource group, open Azure portal > Resource groups, select the group, then Cost analysis > Group by > Cost allocation. Use that view and the checklist with a supplied cost file.
- Access
- Ask an authorized Azure cost-management colleague for the rule settings and read-only allocation results for the source and target scopes you name, covering the billing month under review.
- If you do not use that tool
- Give the colleague the source and target subscription IDs, resource group names or tag keys and values, plus the billing month. Request the rule split, creation order, and Usage Details or Exports rows showing costAllocationRuleName and signed source and target charges.
Why this is worth a look
If teams treat reassigned costs as an invoice change, internal chargeback and payer responsibility can conflict. Azure shows shared costs against consuming subscriptions, resource groups or tags, while chargeback happens inside your organization. Proportional total, compute, storage and network splits use selected target costs for the current billing month, so the result reflects a spending ratio rather than direct shared-service consumption.
Run this check
CHECKLISTComplete this checklist without changing Azure settings. Review one rule across its source and targets for one billing month, recording signed billing-currency amounts and custom percentages.
[ ] Record rule name, review date and billing month: __________
[ ] Confirm agreement: MCA-E | MCA-online | EA.
[ ] Record source type and values: subscription | resource group | tag.
[ ] Record target type and values: subscription | resource group | tag.
[ ] Confirm the review excludes purchases, including reservations and savings plans.
[ ] Record basis: total cost | compute cost | storage cost | network cost | custom.
[ ] For proportional splits, record the current billing month used for target costs.
[ ] For custom splits, record each target's whole-number percentage; confirm total = 100%.
[ ] Record why the chosen basis fits the shared service: __________
[ ] Record creation order and any dependency on another rule: __________
[ ] Record whether up to 24 hours has elapsed since creation: __________
[ ] For a targeted resource group, inspect Cost analysis grouped by Cost allocation.
[ ] In downloaded Usage Details and Exports CSV files, identify the documented rule-name header: costAllocationRuleName.
[ ] Find rows for this rule. For each negative source and positive target entry, record the signed CostInBillingCurrency amount and its BillingCurrency or BillingCurrencyCode.
[ ] Keep the allocated chargeback report separate from invoice reconciliation.
[ ] Record unresolved differences and the colleague responsible for review: __________How to confirm it
- 01
Confirm the costs qualify
Check that the agreement is a Microsoft Customer Agreement bought through a Microsoft representative (MCA-E), one bought through the Azure website (MCA-online), or an Enterprise Agreement (EA). Leave purchases, including reservations and savings plans, out of the allocation review.
- 02
Match the rule to teams
Record the shared-service source and each consuming target as a subscription, resource group or tag. Ask the responsible teams to confirm that these scopes match the internal chargeback boundary.
- 03
Test the split rationale
Compare the chosen basis with how teams benefit from the shared service. Total, compute, storage and network proportional methods use selected target costs for the current billing month. For a custom split, confirm whole-number percentages total 100%.
- 04
Check order and timing
Review rules in creation order, which is their processing order. Note dependencies before recommending a change. Allow up to 24 hours for a newly created rule to take effect before treating missing allocation results as an error.
- 05
Verify signed cost entries
Find the rule in downloaded Usage Details or Exports CSV files under the documented costAllocationRuleName column. Compare signed CostInBillingCurrency amounts, with BillingCurrency or BillingCurrencyCode, for the negative source and positive target entries. For a targeted resource group, use Cost analysis grouped by Cost allocation. Keep this allocation report for internal chargeback, not as evidence that Azure changed the payer.
Before making changes
Assume one existing rule and a cost file covering the same scopes and billing month. CostInBillingCurrency is before credits or taxes, so do not treat it as the final invoice amount. Rules documented here use subscriptions, resource groups or tags as sources and targets. Management groups are not currently supported in Cost Management features for Microsoft Customer Agreement subscriptions.