The Budget Panel shows various information about the budget of your city, including expenses and income from all sources, taxes, bonds, recent transactions, and more.
You can also set taxes from here.
There is also advice such as: "When the board is green, the budget's clan! Upgrade to City Hall to control R,C and I independently
How to access SimCity Budget Panel[edit]
You can either press F3, or Click on the bottom where it says how much Simoleons you have: