So I decided to mess around with the cheat codes to figure out how to make the best sort of economy planet. The preliminary results are extremely non-intuitive however. I think one can probably notice this effect in most games.
A tax rate of 60% for instance does not give you 6 times the income a tax rate of 10% would give you. Some planets with economic bonuses might give 6 times the income but ones without such bonuses will give far less (for instance a population of 5 billion with a 120% tax bonus on the planet will give around 11bc at 10% and 29bcs at 60% tax). So the lower the percentage the more money you seem to get per population. Hence the percentage of taxes doesn't seem to be a straightforward tax percentage at all.
Further support from this comes from comparing a 37 billion population planet with a 5 billion. The former had a 300% economy bonus, the later had a 120% economy bonus. At 10% tax the bigger pop gave only 33bcs in taxes, while the smaller pop gave 11bc (a better rate/pop unit on the smaller world, 2bc/pop vs. less than 1bc/pop). At 60% taxes the larger world did increase by a factor of 6 (almost), to 197bcs, and the smaller one by just a factor of 3 to 29bcs. Given that the bigger world have a 300% econ bonus vs. the smaller ones 120% econ bonus, however, means that the larger world had less of an improvement overall.
If someone understands what is going on here (weird diminishing returns, does morale matter to some extent--note that both worlds had 100% morale/approval at 10% taxes), then please share. I find this very annoying however, since you think a simple percentage such as "tax rate" would be rather straightforward. It simply isn't directly proportional to population or even itself! Seems like madness to me. At the very least doubling the tax rate should double your revenue before expenses.
