> Those changes alone, with absolutely no spending changes, balance the budget.

I tried out the calculator and put in all your changes, and the budget wasn't balanced, there was still a 1.4T deficit (as opposed to the current 1.9T deficit). The app only claims the budget is "sustainable" now because it assumes GDP keeps growing at the same rate (which might not be true), and if so we'll hit a 3%-of-GDP "deficit target" in 25 years. Also adjusting a negative tax rate kind of seems like it is, in fact, reducing spending (i.e. the federal government reduces the amount of tax credits it gives out). This also assumes the federal government will not introduce new programs, new spending, etc. So really all you did was reduce the deficit by .5T along with a hope and a prayer that the economy will continue to grow at the same rate for the next 25 years (while at the same time the federal government does not increase spending). I personally think it's bad to have a deficit at all and that we should work towards zero deficit and eventually surplus (yes, I know there are all sort of growth hacks and such you can do with debt, but historically politicians have succumbed to slippery slope deficit increases and so for that reason alone I think holding politicians to a zero deficit standard is best -- do it for a few generations and now there's a precedent that protects us from getting into the situation we are currently in). To me a "balanced budget" is that your spending is <= your income.

Anyway, interesting calculator app. I do see the value in raising taxes for sure, but it's not easy politically to raise taxes and it's also not easy politically to cut spending (whichever group likes the thing you cut will scream), so ultimately it might have to be a hybrid solution where democrats increase taxes without increasing spending when they are in power and republicans cut spending without decreasing taxes when they are in power. When I say that out loud though it seems like a pipe dream, sigh...