For example, most folks have heard that when tax rates are reduced the govt winds up collecting larger revenues.  Conservatives have long recognized this factor, and even Obama and JFK recognized that this indeed happens.  Higher rates means the economy will contract, and lower tax rates mean expansion of employment, wages, profits, growing revenues and financial reserves.

Its sometimes call dynamic scoring within the estimates, vs static scoring in the estimates and studies.   

Also when the static scoring is (too often) used, it gives rise to dire predictions --the chicken little effect.  

When you said: "Social Security has to be taxed or Social Security will become insolvent" you ignored other changes, like making overtime and tips tax free.  Those will also reduce some funds going into Social Security reserves.   

Hmmn  Seems that's selecting winner & losers.   Current workers would benefit from not taxing tips & overtime, whereas retirees would benefit from not taxing social security.  Seems fairer to include all three kinds of benefits.

There's been no other Prez matching the big investments coming into the US from Trump's attractive business conditions.  New investment from the $$$  trillions coming in.   Unheard of size  & varieties of new and expanding industries.  Thus providing huge employment increases.  Growth in payrolls means growth in Social Security tax collections, bolstering those financial reserves.  Dynamic scoring of estimates.

All adds up to strong growth that the US economy will be seeing.  From the lower tax rates as well as the bigger pie.   And that's the missing component in the dire or chicken little predictions within the Dem's favorite studies.