One tier table. Two very different payouts.
Enter your tiers and period volume. The calculator computes the retroactive reading (final rate × all volume) and the incremental reading (each rate inside its band) side by side — because which one your contract means is worth real money.
Email me this calculation + the tier-design guide
Your numbers, both readings, and the checklist for finding out which design your contract actually means — useful to forward to your controller.
We’ll email your calculation and may follow up once about the working session. No list, no reselling. Aurgus is in design-partner stage.
Doing this in Excel?
The formula isn’t the hard part — retroactive is a LOOKUP of the achieved rate × total volume; incremental is a SUMPRODUCT across band widths. The risk is everything around the formula: it encodes one design while the contract means the other, it silently survives renewals, and it recomputes history when late data lands — with no record of what was booked. That gap between a calculation and a governed calculation is what the tiered rebates guide covers.