Payroll management

I disagree. If you don’t manage contracts correctly, I doubt you can make payslips.

Contracts, leave, holidays and legal.
For example; you work on Sunday : 25% more, different fiscal rule, and 1/2 a day off as compensation.
Another one: You get credit for training, you use part of it, and during this training you don’t benefit of lunch tickets. and so on…

yes indeed
This is why I mention it.

Not only (part of) expense. Totals of paid, raw, different total for pensions, fical fees and so on.
Part of expense is in because it may be reincorporated in salary (company car, tele-working expenses etc…)

Importing rules from csv format ?

It may be of interest because it is similar to what you propose.