This is the simple way to set taxes


The first tax setting is your basic Tax rate for the beginning of the game. The threshold for this tax is 200 for the start of the game, as you don't have that much money anyway. In order for a Ratizen to advance to the next tier a value of 500 wealth is required as well as necessities. This basic tax will be changed to ~600 later once you have the wealth to support higher tier Ratizens.


The second tax setting is there to limit the high earning Ratizens from saving too much wealth


As you can see the Hunter gets much more income than an Lumberjack

Now to keep all rats financed to cover their daily expenses we need to set a Subsidy for them I set the minimum threshold to 100 to begin with as there aren't many necessities early for them to purchase, but later you may consider increasing this to 200-300, once you are promoting wealthy Ratizens. Obviously the margins are slim with these numbers, and you will occasionally end up with Ratizens begging for money/food. We will fix that later.

To prepare for trading we will need to start making Bread. We must ensure we have sufficient Grain and Water. Bread is better and more efficient food source than Grain, so it's good to upgrade to it Early game. Don't forget to allow your Ratizens to eat Bread, by creating a Policy

This is the best way to boost your economy. Once you get the Bank, you will have Dialogue Option to decrease or increase the Value of money. Obviously if you are buying Dar you need to increase the value of Pia. If you l want to sell Dar for Pia, you decrease the value of Pia.

Once you get the School, you will be able boost your Intelligence so your other skills can level faster

Don't forget to deal with Criminals. You can either do it yourself by building Prisons, or by hiring a Ratizen to work inside a Police Station.

Once we start trading with other nations and sell our Dar currency we shall have enough Money to start getting ready to promote our Ratizens to higher class. Note we are now taxing their
Income
Also we must adjust the High Savings Tax

Because now we have more Necessities produced, we must provide more Money to our poorest Ratizens.