Migration Economics and TCO

Understand source run rate, target run rate, transition cost, TCO and payback.

CoreFinOps models the financial case for a workload migration in explicit currency using exact decimal arithmetic. The model should preserve both user inputs and derived outputs so the decision can be reproduced.

Primary figures

Current source run rate: recurring legacy cost on the modeled basis.
Target AWS run rate: projected future operating cost after transition.
Transition cost: one-time project, migration and other supported transition expense.
Dual-run cost: temporary overlap while old and new environments remain operational.
1-year / 3-year TCO: comparable total modeled cost over the stated horizon.
Monthly saving and payback: scenario outputs, not guaranteed billing outcomes.

Assumptions and confidence

An AWS rate estimate and a customer-provided legacy support contract should have different provenance. Unknown licensing, shared-service attribution or target sizing may warrant sensitivity ranges instead of a single false-precision number.

Important

Monthly saving and payback figures are scenario outputs from the modeled inputs. They are not guaranteed billing outcomes and must not be presented as verified savings.

Comparison rules

Compare the same currency, period and cost basis. Do not add USD and EUR without an approved exchange-rate model. Do not treat an estimated post-migration run rate as observed AWS spend.

After migration

The model provides the planned benchmark. Dual-run, decommission and subsequent value verification establish what actually happened. If actual evidence contradicts the model, record the difference without rewriting the original approved decision case.