Riley brings up a good point - we need to figure out how extensive we want our taxes to be. In real life, there is quite a long list of excise taxes, as well as individual and joint tax brackets. Do we want to keep things reasonably simple as we have done in the past, or do we want to try and model it closer off what America does?
While I am not a member of this esteemed body, I urge Congress to keep the budgetary process as accessible and inclusive as possible. Keep in mind that most of the people who play this game are not tax experts: we need to make sure that we're not shutting them out of the process by creating a budget so intricate that only a few elite players can understand it.