Call it a loophole, tax fraud, or government at its most outrageous, but it’s got to stop.

The federal government is currently handing out $4.2 billion in taxpayer-funded checks a year to illegal immigrants.

This isn’t some service benefit that illegal immigrants are receiving like taxpayer-subsidized healthcare or education. And it’s not a tax deduction or credit that requires the recipient to actually pay any taxes. It’s a taxpayer-funded check from the federal government via the refundable Child Tax Credit program. And there’s absolutely no proof required that the recipient actually be eligible under the law, which illegal immigrants are not.

Abuse of this tax benefit is one of the most ridiculous factors adding to our country’s federal deficit today. Equally harmful, it is acting as a powerful incentive for more illegal immigrants to come to America — a magnet for more and more illegal crossings and activity.

While it is true that illegal immigrants can’t qualify for legitimate Social Security numbers and use them to file income tax returns, many illegal immigrants have discovered that the IRS allows them to apply for Individual Taxpayer Identification Numbers (ITIN). And the overwhelming majority of returns filed using ITINs are filed by illegal immigrants — this is how they fraudulently apply for and receive these checks.

This tax credit was designed to help working families offset the costs of raising children. But the practical reality is that illegal immigrants — who don’t possess valid Social Security numbers because they are not authorized to legally work in this country — are currently able to receive these tax credits by simply providing an ITIN and claiming children who might not even live in the United States. So, American taxpayers are writing checks to illegal immigrants — $1,000 per child, $4.2 billion per year total.

An investigative reporter in Indianapolis recently uncovered cases in which illegal immigrants were claiming the Child Tax Credit for nieces and nephews who did not even live in the United States. Some received more than $10,000 from the federal government.

One illegal immigrant interviewed in Indiana admitted that his address was being used by four other illegal immigrants who don’t live there. They claimed 20 children were living in one mobile home and received tax returns totaling $29,608. But only one child was observed to actually live at the residence. The 19 other children live in Mexico and have never visited the United States.

The Obama administration’s own Department of Treasury, through its Inspector General for Tax Administration, has repeatedly warned about these abuses and said that “millions of people are seeking this tax credit who, we believe, are not entitled to it.”

Tragically, the IRS is doing nothing to police against this blatant fraud. While I believe it could and should, the agency’s complete inaction has prompted me to introduce a clear solution in Congress — the Child Tax Credit Integrity Preservation Act — that would prevent illegal immigrants from claiming these tax credits intended for hard-working American citizens.

My bill is simple and workable. It would require every individual applying for the Child Tax Credit to provide a valid Social Security number, exactly as everyone must do to receive the earned income credit.

Sen. Jeff Sessions (R-Ala.) and I took to the Senate floor recently to ask our Senate colleagues to pass this common-sense bill by unanimous consent.

Unfortunately, none other than Senate majority leader, Harry Reid (D-Nev.), blocked our effort.

This reform is badly needed. We must act — particularly now, in tough economic times, when every American family is scrubbing its budget and demanding that Congress do the same. So I’ll keep fighting until it’s done.

The American people have the innate common sense and fairness to see this plain as day. The question is: will this U.S. Senate muster up those same qualities and do the right thing?

Vitter is the founder and chairman of the Senate Border Security and Enforcement First Immigration Caucus. This piece originally appeared at The Hill.