Why

Undocumented allocation rules create a single point of failure — if the person who built them leaves, nobody knows how costs are split. Version control provides audit trails and prevents silent breaking changes. Quarterly review ensures rules stay aligned with organisational changes (reorgs, new BUs, new shared services).

What

Document all allocation rules in a version-controlled, auditable format with assigned ownership and a quarterly review cadence.

How

Catalogue All Active Allocation Rules

For each rule, document:

Field	Example
Rule name	Platform Infrastructure — Even Split
Source	Accounts: `acme-infra-*` (networking, security, logging)
Targets	All BU accounts (Finance, Marketing, Engineering)
Method	Even split (33.3% each)
Driver	N/A (equal benefit)
Monthly cost	~$48,000
Implementation	AWS Cost Category “Shared-Platform”
Owner	FinOps Lead
Last reviewed	2026-01-15
Next review	2026-04-15

Store in Version Control

Recommended: Git Repository
───────────────────────────────────────────
  /cost-allocation
    ├── rules/
    │   ├── platform-infrastructure.yaml
    │   ├── data-lake-proportional.yaml
    │   ├── commitment-redistribution.yaml
    │   └── ...
    ├── CHANGELOG.md
    └── OWNERS.md

Alternative: CMDB / ServiceNow configuration item, or a page in your FinOps wiki with change history enabled.

Establish Review Cadence

Cadence	Activity
Quarterly	Review all rules. Check for: new BUs, retired applications, reorgs that change target weights, new shared services.
On-event	Trigger review when: a new BU is created, a shared service is decommissioned, an organisational restructure occurs.

Deliverable Checklist

All active allocation rules catalogued
Rules stored in version control or auditable system
Each rule has a named owner
Quarterly review cadence in governance calendar
CHANGELOG started for audit trail