Help --> States --> Household --> Budget
Each year in winter, when you did not already work on a task or enforce a reform, you may change some values in the budget. The possible height of the changes depends on the influence of the regent and reaches from 4% to 50%. The number of the percentage won't be added, an increasing of the capital taxes from 2% at 12% does not result in 12%, but in 2,2%.
Helpmenu