CBO estimated that extending the expiring TCJA individual provisions would cost roughly $4 trillion over a decade, so the $4 trillion figure is in the right ballpark for revenue loss; however, framing this revenue effect as a "tax increase on the American people" overstates broad impact since most Americans would face only modest changes and the largest dollar effects are concentrated among top earners.

• factcheck.org· review article
• cbo.gov· evidence