R1 | Congressional Budget Office | The Budget and Economic Outlook: 2018 to 2028 | April 2018 (published April 9, 2018) | Appendix B, What Are the Act’s Projected Budgetary Effects? and Summary Table 2. https://www.cbo.gov/publication/53651 ; U.S. National Library of Medicine archive of original PDF https://digirepo.nlm.nih.gov/master/borndig/101732141/53651-outlook.pdf

To construct its baseline budget projections, CBO incorporated the effects of the tax act, taking into account economic feedback—that is, the ways in which the act is likely to affect the economy and in turn affect the budget. Doing so raised the 11-year projection of the cumulative primary deficit (that is, the deficit excluding the costs of servicing the debt) by $1.3 trillion and raised projected debt-service costs by roughly $600 billion. The act therefore increases the total projected deficit over the 2018–2028 period by about $1.9 trillion.

Before taking economic feedback into account, CBO estimated that the tax act would increase the primary deficit by $1.8 trillion and debt-service costs by roughly $450 billion. The feedback is estimated to lower the cumulative primary deficit by about $550 billion, mostly because the act is projected to increase taxable income and thus push tax revenues up. And that feedback raises projected debt-service costs, because even though the reduction in primary deficits means that less borrowing is necessary, the act is expected to result in higher interest rates on debt, which are projected to more than offset the effects on debt-service costs of the smaller debt. On net, economic feedback from the act raises debt-service costs in CBO’s projections by about $100 billion.

Summary Table 2. CBO’s Baseline Budget Projections. In Billions of Dollars; actual 2017, projected 2018 and 2019.
Revenues | 3,316 | 3,338 | 3,490
Outlays | 3,982 | 4,142 | 4,470
Deficit | -665 | -804 | -981
Revenues as a Percentage of Gross Domestic Product | 17.3 | 16.6 | 16.5

R2 | U.S. Treasury Bureau of the Fiscal Service | Financial Statements of the United States Government for the Fiscal Years Ended September 30, 2019, and 2018 | issued February 27, 2020 | Statements of Changes in Cash Balance from Budget and Other Activities. https://fiscal.treasury.gov/accounting/us-financial-report/2019/statements-of-change-cash-balance

United States Government
Statements of Changes in Cash Balance from Budget and Other Activities
for the Years Ended September 30, 2019, and 2018
(In billions of dollars) | 2019 | 2018
Total budget receipts | 3,462.2 | 3,328.7
Total budget outlays | (4,446.6) | (4,107.7)
Budget deficit | (984.4) | (779.0)