We have enough experience with supply side economics to permit the CBO to attempt to project what the likely outcome of Trump tax cuts will be on government revenue and deficits. (Of course, since these projections deal with the future, rather than the past where 100% accuracy is achievable, they are subject to substantial error. )
net revenue = revenue - expenditure ; when revenue > expenditures , net revenue is positive and a surplus is produced.
Unfortunately the relationship is complex because revenue = f(expenditure); the form of this function and the values of its parameters are the subject of debate. We can, however, say that it is generally true that when the government increases the amount spent into the economy compared to the amount it withdraws in revenue, savings are increased by the difference, and there is a consequent increase in investment and economic activity. This in turn results in increased tax revenue.; when revenue < expenditures , net revenue is negative and a deficit is produced.
In the case of the initial and substantial Reagan tax cuts, revenues did increase but not nearly so much as spending increased and the net results was ballooning deficits. There have been many economic studies of this experiment in tax rate reduction. Economists have concluded that huge increases in government expenditure, and the consequent recovery from recession -- also helped by tax reductions-- were responsible for the increases in revenue. The government in that instance actually leveraged up well in excess of the private sector's leveraging down during the recession that existed when Reagan took office. After the Reagan cuts and huge increases in spending, the economy nicely recovered. Ballooning deficits soon caused the Congress to take back some of the cuts. The final result by the end of the Reagan era was a dramatic increase in the national debt, and a strong economy. Deficits equal additional private sector savings and huge deficits equal huge additional private sector savings. The distribution of those savings is another matter however.
it's actually very simple math, and the benefit is obvious -
- for the US on it's own, the tax rate should not matter, because 1 dollar out of the gov's pocket is now 1 dollar in the private sector. and that 1 dollar in the private will always work more efficiently than in the gov's pocket;
- but the US is not isolated. on this globe today money flows like water towards gravity, towards low tax rate... as a consultant I have worked on projects for multiple F500 companies to shift tax burden to lower rates... very simple - global companies have separate legal entities that deal with each other, and the price structure is set up such that big portion of the profit is shifted overseas.
so you see, tax cuts come down to 2 simple maths, both bring benefits to the economy.