Loud and temporary
A fixed amount per qualifying deal for a short period, paid fast. It moves attention immediately and loses effect if it is always on.
Separate from the plan
Run spiffs beside the main plan, not inside it, so they can be switched off without renegotiating anything.
In Prowi
Create the plan, pick the measurement point and period, set the rule, assign it to roles. From there every closed deal in your CRM is priced live, the rep sees it in the app, the manager approves, and finance exports the file. When data changes, the correction follows automatically.