It shouldn't trouble you. Consider "if you have money coming in." What's "money coming in?" You could tax money transfers, but then my sending $10 from BofA to Citi would invoke a tax. Okay, so if the person on both accounts is the same no tax. Fine. What if some sends $10 from a sole account to a joint account? What if it's from a natural person to their single-member LLC? Et cetera, et cetera.
Broadly speaking, federal income taxes take down about 10% of GDP and payroll taxes a further 6% [1].
[1] https://en.wikipedia.org/wiki/Income_tax_in_the_United_State...
Well, we don't (AFAIK) know the total amount of non-GDP transfers of wealth that occur. If you limit taxed transactions to just the transactions that show up in GDP, then it's equivalent to asking what the current tax-to-GDP ratio is, which is easy to look up (it's much higher than 10%.)
Would that increase or decrease the amount of taxes?
The fact that I can't even answer that simple question troubles me.