The Congressional Budget Office (CBO) has released their latest outlook for the next decade and, to make a long story short, the CBO expects the GOP's tax cuts will contribute to GDP growth but the tax cut package won't pay for itself.
The CBO projects the federal deficit will reach $800 billion for the current fiscal year (which is already half over) and increase to at least $1 trillion in fiscal 2019.
From the Associated Press:
The CBO report says that that the twin tax and spending bills will push the budget deficit to $804 billion this year and just under $1 trillion for the upcoming budget year.
CBO says economic growth from the tax cuts will add 0.7 percent on average to the nation’s economic output over the coming decade. Those effects will only partially offset the deficit cost of the tax cuts. The administration had promised the cuts would pay for themselves.
The projection that tax cuts will add an average 0.7 growth is far more generous than others have estimated. Economists at Harvard just recently estimated that tax cuts will add just 0.04 percent growth per year.
My gut says growth from tax cuts will probably fall somewhere in between those numbers, but these are just baseline projections that can't necessarily tell us what will happen in the future.
For example, the CBO's projection can't tell us what another devastating hurricane season could mean or tell us what will happen if Trump's trade war causes a recession.
In other words, the CBO's current projection is actually a best-case scenario.
You can read the CBO's full report here.