I hope that's not right. Because then there is no reason to be communist. It would be to your disadvantage if that method was used. Example....
Say you have 2 cities. Both generate 10 trade (before corruption). You have tax on 100%.
City A has zero corruption, so under a Monarchy it would make $10 per turn. City B is far away from the capital, and only 2 of the 10 trade is not lost to corruption. So that city makes $2 per turn.
In City A, you build a marketplace to increase income to $15, then you build a bank to increase income to $22. You do not build a marketplace or bank in City B, because you would not profit from it. So the total cost of building 1 marketplace and 1 bank is $4, but it increases income by $12. So it is a net profit of $8.
Now, say you have this same situation, but in a communism. The total amount of trade not lost to corruption would be 12, so 6 for each city. So each city makes $6 per turn.
In this situation, it would be to your advantage to build a marketplace and a bank in both cities. A marketplace would increase each city's income to $9, and the bank would increase it to $13.
The cost of 2 marketplaces and 2 banks is a total of $8. The cities' income increased a total of $14. Deducting the costs, these two cities only made a net profit of $6.
Clearly, monarchy kicks the crap out of communism.
Trada, if that truly is the way that the game determines the level of corruption, then I fail to see why anyone would use a communist form of government. It is obviously better to be a monarchy. Can anyone explain to me why you use communism?