He said four other illegal immigrants file tax returns using his address, even though none of them actually lives there. And he said this year, those four workers filed tax returns claiming 20 children live inside his small trailer home. As a result, the IRS sent the illegal immigrants tax refunds totaling more than $29,000.

Wthr story

From Indiana to Capitol Hill, thousands of people are now weighing in on a WTHR investigation exposing a tax loophole worth billions for undocumented workers. But what, if anything, can be done about it?

Note: This is part two in a two-part series. Read part one here.

INDIANAPOLIS - Congressman Dan Burton (R – Ind) is frustrated – very frustrated – after learning the details of an Eyewitness News investigation.

"Why in the world are we doing this?" he asked. "Are you kidding me? The cost to the American tax payer is huge!"

The veteran lawmaker is responding to what 13 Investigates discovered all across Indiana: illegal immigrants getting big tax refunds from the Internal Revenue Service thanks to a loophole in federal law.

MORE: Tax loophole costs billions

The loophole allows undocumented workers to collect what's called an additional child tax credit. The credit – up to $1,000 per child – can be claimed even by families who pay nothing in taxes, in many cases resulting in a cash payment from the IRS. It is intended for working families with children who live in the same home.

But a local tax preparer came to Eyewitness News to blow the whistle on millions of people who, he believes, are taking advantage of the system. He says many illegal immigrants are claiming the tax credit for children who've never lived in this country, and he showed 13 Investigates dozens of redacted tax returns to prove his point.

"There is not a doubt in my mind there is huge fraud taking place here," said the whistleblower, who asked not to be identified for fear of reprisal. "I can bring out stacks and stacks. It's just so easy it's ridiculous."

Exposing the loophole

An undocumented worker in southern Indiana told 13 Investigates just how easy it truly is.

He said four other illegal immigrants file tax returns using his address, even though none of them actually lives there. And he said this year, those four workers filed tax returns claiming 20 children live inside his small trailer home. As a result, the IRS sent the illegal immigrants tax refunds totaling more than $29,000.

But none of the 20 children listed as dependents on the tax returns lives in Indiana – or even in the United States.

"No, they don't live here," admitted the undocumented worker, who lives with his young daughter. "The other kids are in their country of origin, which is Mexico."

The IRS granted tax credits for the 20 children anyway, even though the agency's own policy states they are not eligible. (Children are eligible for additional child tax credits only if they are US citizens or minor resident aliens who live in the US with a tax filer for more than half of a calendar year.)

According to WTHR's whistleblower, cases like this one are commonplace because the IRS does little to verify the eligibility of both the undocumented workers filing for additional child tax credits and the dependents listed on their tax returns.

13 Investigates has confirmed it's a growing problem. It's nationwide. And it's out of control.

Billions already paid

Eyewitness News obtained US Treasury Department audit reports that show illegal immigrants now get additional child tax credits totaling $4.2 billion dollars each year. The department's Inspector General for Tax Administration has repeatedly warned the IRS that undocumented workers are abusing the additional child tax credit.

"Millions of people are seeking this credit who, we believe, are not entitled to it," said inspector general Russell George. "We have made recommendations to [IRS] as to how they could address this and they have not taken sufficient action in our view to solve the problem. It's very troubling."

Why has the IRS done nothing?

Despite phone calls, emails, even a visit to IRS headquarters in Washington to get answers, no one at the IRS would meet with WTHR.

The agency instead sent 13 Investigates a short statement (see below) saying it is following the law, and current tax law does not prevent undocumented workers from getting additional child tax credits. The IRS claims it can't change that without a new law.

Rep. Burton and other lawmakers are now ready to act.

Lawmakers looking for a fix

"We've got to deal with it," he said. "I knew this was a problem, but until hearing what you found, I didn't know it was this severe."

Rep. Burton and dozens of other House Republicans have co-sponsored a bill that would essentially authorize additional child tax credits only for US citizens. House Resolution 1956 would require tax filers to provide a valid social security number to receive an additional child tax credit.

The IRS provides illegal immigrants with an ITIN (individual taxpayer identification number) so they can file tax returns, but most undocumented workers are not eligible to receive a social security number.

HR 1956 has sat idle in the House Ways and Means Committee for almost a year.

However, language from the bill is now included in a package of proposed budget savings measures that House lawmakers are expected to consider in May. While the budget package may have enough support to pass the House, it is expected to die a quick death in the Democratic-controlled Senate.