Admin - Cost Items
The cost lines the pricing simulation works on (Stripe, invoicing, taxes, and annual overheads such as servers, accountant, lawyers, bank fees), versioned by the day they enter into force.
Every version of the cost lines
Each row carries its state, derived from the dates: future, in_force or past.
Schedule a new version of a cost line
Adds a cost, or changes one from a day on: the version before ends the day before. A decorrence in the past, or two versions of the same line starting the same day, are refused.
The cost lines a simulation would use
In force on the day, for the regime: the regime's line wins over the general one, and the tax parameters come back derived into one income_tax line.
Cancel a version that is not in force yet
The previous version reopens. A version already in force is history that settled months were computed with: it can only be superseded by scheduling a new one.