If you look at when the tax bill passed, it’s not clear at all that an increase in tax receipts followed the bill’s passage. Because the Treasury report also includes month-by-month data, it’s possible to drill down to measure trends during more specific time periods.
For the three months of fiscal 2018 prior to the tax cut, individual income tax collections rose by 10.8 percent over the equivalent period from 2017. But the rise for the seven months after the tax cut was 6.7 percent.
And if you look at total tax collections from every category, rather than just individual income taxes, the picture is even worse. During the seven-month period after the tax bill passed, total receipts actually fell slightly compared to the equivalent period in 2017, by about a tenth of a percentage point.
Perhaps the most revealing comparison takes in the May-to-July period, because it excludes the spike in payments in April, when most Americans pay taxes on income generated in 2017, before the tax law was passed. During that period, individual income tax collections fell by about 1 percent compared to 2017.