Chargeback Calculator

team charge = direct cost + (shared pool + untagged cost) × allocation share, where the share is 1 ÷ teams, direct cost ÷ total direct cost, or the team weight ÷ total weight. Chargeback moves the whole invoice onto consuming teams, which means the shared platform layer and any untagged cost must be pushed somewhere rather than absorbed centrally. The allocation key decides who pays: an even split is simple but punishes small teams, proportional tracks usage and is the common default, and a weighted key lets you encode a business judgement such as revenue or headcount.

The moment cloud cost lands in a team's own budget, behaviour changes — but so does the argument, because the shared-cost key is where every dispute happens. Publishing the key and driving the unallocated residual to zero is what makes chargeback defensible; this is a modelling aid, not accounting or tax advice.

This calculator takes 9 inputs: Team A direct cost, Team B direct cost, Team C direct cost, Shared platform cost, Untagged cost that must still be recovered, Shared-cost allocation key, Team A weight, Team B weight, Team C weight. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Chargeback transfers real budget: 100% of the invoice lands in consuming teams' cost centres and they answer for it. Showback reports the same numbers without moving any money, so the central platform team still holds the invoice. Showback is the usual first step because it exposes the allocation disputes before money is at stake.