In a prior analysis, we estimated that the average net fiscal cost (taxes paid minus services used) of an illegal immigrant was $65,292 during their lifetime — excluding their U.S.-born children. This came to $65.3 billion per million illegal immigrants. The figures were expressed in 2016 dollars. Adjusted to 2018 dollars, it would be $69,570 per illegal immigrant, or $69.6 billion per million illegal immigrants.

This net figure is based on estimates of the fiscal impact of immigrants by education level developed by the National Academies of Sciences, Engineering, and Medicine (NAS). My analysis takes the education level of illegal immigrants and applies it to the lifetime net fiscal deficit, or fiscal surplus, created by immigrants at each level of education. As we pointed out in the earlier analysis, the cost of a deportation (technically referred as a removal) is much less, averaging only about $6,000 to $11,000 per person.

The reason illegal immigrants are unambiguously a net fiscal drain is that less-educated people, native-born or immigrant, earn on average modest wages and as a result they tend to make modest tax contributions, while needing significant social services. As we pointed out in our prior study, research by the Center for Immigration Studies, the Pew Research Center, the Heritage Foundation, and others have all found that a very large share of illegal immigrants have relatively few years of schooling — most have not completed high school or have only a high school education. The fiscal drain illegal immigrants create is not because they are all lazy and on welfare, nor it simply because they often work off the books and don't pay taxes. Rather they tend to earn wages commensurate with their education levels and, as result, they typically have low incomes on average, though there are individual exceptions. Those with low incomes as a group, regardless of legal status, use more in public services than they pay in taxes. It's why cities and states worry so much about losing their middle- and upper-income tax base. It is middle- and upper-income residents who pay most of the taxes, which does not describe the average illegal immigrant.

As we pointed out in our prior analysis, the above cost estimates do come with some caveats. The NAS projects future fiscal impacts, so it provides a good idea of the fiscal savings of keeping someone out to the country moving forward. However, a significant share of the current illegal population are not recent arrivals, so some of the net burden they create has already accrued. We previously estimated that one-fifth of the average fiscal deficit the current population of illegal immigrants creates has already been incurred by taxpayers. This reduces somewhat the fiscal benefit of removing an existing illegal immigrant, but the fiscal drain is still much larger than the average cost of a removal.

A second caveat is that the above cost estimates are only for the original illegal immigrant, and exclude descendants. Using the NAS net cost estimates for the descendants adds $18,112 (2018 dollars) to the net fiscal drain per immigrant. A third caveat is that the estimate for deportation costs does not include the costs of the immigration courts run by the Department of Justice. Dividing the court's budget in 2016 by the number deportations in that year adds $1,864 to the average cost of a removal or it adds $820 to the 2012 cost — in 2018 dollars. Finally, the NAS's long-term fiscal estimates by education use the concept of "net present value" (NPV), which is commonly employed by economists. This approach has the effect of reducing the size of the net fiscal drain that unskilled immigrants create because costs or benefits years from now are valued less relative to more immediate costs. If the NPV concept is not used, the actual net lifetime fiscal cost of illegal immigrants is likely $125,000 to $135,000 per illegal alien, or nearly twice the cost when the NPV concept is employed.