Cost-migration ledger
A small record attached to a meaningful AI change that lists, for each cost dimension, the before, after, delta and owner, so shifted costs stay visible across budgets.
A cost-migration ledger is the working artifact of the cost-migration test. Instead of tracking one headline "AI cost" number, it is attached to each meaningful change to the AI system and records the deltas that change caused.
Each cost dimension uses the same four fields: Before · After · Delta · Owner. Typical dimensions include:
- Model and inference cost
- Retry and tool-call cost
- Human review time
- Exceptions and escalations
- Failure and recovery work
- Governance and assurance effort
- Accepted or completed outcomes
- Cycle time and service level
Why a ledger of deltas
A single number hides who absorbed the change. The owner column is the point: a saving that lowers engineering spend but raises operations workload is only a saving if the organization decides it is, on purpose, with both owners aware. Keeping deltas also gives finance and operations a shared record, so a total cost of ownership figure can be attributed before it is optimised.
Read more in A cheaper AI model can move the cost instead of removing it.
Related terms
Cost-migration test
A check that traces every apparent AI saving across budget owners to see whether the cost was removed or merely moved into review, exceptions, recovery, governance or adoption.
Total cost of ownership
The full cost of running an AI system across its life: model and inference spend plus integration, human review, exceptions, recovery, governance and maintenance — not just the price per call.
Cost per accepted outcome
The total cost of getting one AI-assisted result that is actually accepted and used, counting model spend, retries, human review, exceptions and recovery — a truer measure than cost per call.