The capacity unit on the contract is not the unit on the deployment.
MIPS capacity contracts are the largest single line item most enterprises carry on their software estate, and the definitions on the paper were written for a generation of z systems that no longer matches how capacity is actually provisioned. The renewal quote arrives priced against the old chunk model. The deployment runs on the new sub capacity model. The gap between the two is where most of the negotiation envelope lives.
The desk treats every MIPS renewal as a reconciliation problem before it is a pricing problem. Three things have to line up before the quote can be honestly evaluated. The capacity definition in the contract. The sub capacity reporting from the current deployment. The growth allowance clause that decides what happens when actual usage diverges from the contracted ceiling. Only after those three are reconciled does the renewal envelope become legible.
The seller's renewal team is not trying to overcharge. The seller's renewal team is pricing against the paper. The paper is what the buyer signed. The buyer signed paper that has not been refreshed in three capacity reporting cycles. The opening quote follows mechanically. The negotiation begins with the buyer rebuilding the capacity map from scratch and presenting it back, with a request to reprice on the actual current unit rather than the inherited contractual one.
Growth allowance is the second front. The clause typically reads as a ceiling expressed in MIPS, with overage priced at full list. When the deployment grows through normal business expansion, the overage line reprices everything. The desk negotiates a band, a phased uplift, or a soft ceiling with a true up cycle that the buyer can model. Each of those changes the renewal economics by a different amount, and the right pick depends on the buyer's actual capacity trajectory, not the seller's standard template.