Visual Guide Taxes In Empire: Total War Campaigns 

When I first played the game at release, I ended up bank-rolling the world on low taxes because of the wealth that well-developed regions were giving me. It's been a decade so I'm fuzzy on the details, but I think the basic logic mirrors real-life; when you don't tax people heavily, they have more money to spend which they invest into the economy (growth). The more money the economy makes, the more money the government makes through commercial tax. So if you get money off well-developed land, it's wiser to play the long-game and not tax people to the hilt, because it'll pay dividends when that money improves the regions (which you later draw money from) instead.

Most of the way through the video now, nice experiment, I would add the following thought. This tax method is superior not because you make the same per turn at the end of the experiment, with more growth, but because with the greater town wealth you can always increase the tax when you desperately need funds. The maximum is better. Just a thought! Speaking of which, what do you think about trade - would love to see a video about trading and trade mechanics.

A bit late to the party here but anyway, there is a method that takes the low tax approach to the maximum. As you have shown, only about 13 turns into the campaign you are already ahead and if you now increased the taxes the difference would be even bigger. What I do is the following, I use low tax throughout the entire campaign and every now and then, approx all ten turns, I bump up the tax for one turn, either to level 3 or even 4. This won't cause any problems because you get one turn of grace period before people start rioting. You can use that turn to make mountains of cash and then turn it back down and nobody is angry with you any longer. By 1750 the difference is so vast that you can easily double your income doing this.

Oh nice thanks for the tips