A common misleading claim this fall has been that tax revenues have increased, even with the large tax cuts enacted last year. While it is technically true that fiscal year (FY) 2018 nominal revenue is higher than FY 2017 nominal revenue, revenue has fallen by more meaningful metrics. It has fallen in nominal dollars when comparing tax year to tax year and has fallen in real dollars and as a share of GDP under any scenario. Focusing specifically on revenues raised under the new tax code, revenue has declined by between 3.5 and 8 percent.

This is an updated version of our previous factchecks in August and September, now that FY 2018 has ended and final revenue numbers are available.

Nominal revenue did increase, according to Treasury's fiscal year-end report, which shows that total federal tax revenue is up only $14 billion, or 0.4 percent, between FY 2018 and FY 2017. This revenue growth rate is the eighth lowest in the past 50 years, and the seven lower years either coincided with a recession or tax cuts/expiring tax increases enacted shortly after a recession.

However, this nominal increase is well below the rate of inflation – meaning that the value of revenue collection has actually declined in real terms.

By our estimate, total revenue over the time period in question has actually fallen by 1.5 percent in real (inflation-adjusted) terms. Measured relative to GDP – a sensible way to measure because a steady tax system would be expected to capture roughly the same share of the economy each year – we estimate revenue has fallen 4.3 percent. Finally, relative to the revenue increases that had been previously expected from population growth, inflation, wage growth, structural elements of the tax code, and other factors, tax revenue is down by 5.7 percent.

Yet even these numbers understate revenue losses between 2017 and 2018 because they count revenue raised in FY 2018 but under 2017's pre-tax cut laws.

Increases in certain revenue relative to last fiscal year are driven primarily by non-withheld tax payments made in April (and March) to cover last year's taxes and also by revenue raised in October, November, and December of 2017 – months which are part of fiscal year 2018 but were under the old tax code.

Excluding revenue collection related to last year's code, total nominal revenue is down 3.6 percent, real revenue is down 5.4 percent, and revenue as a share of the economy has decreased by 8.1 percent.

A simpler way to look at revenues for just the tax year would be months after the April 15th deadline for most filers to pay taxes for the previous year. Revenues from May through September have fallen by 4.7 percent in nominal terms.

In other words, revenue has dropped substantially by any measure post the December tax bill. Tax cuts reduce revenue; they don't increase it. While the tax bill does appear to be boosting economic output, that increase in growth won't be nearly enough to offset the substantial costs of the bill.