Christina Segundo-Hernandez and Jose Segundo have worked for years, building a life for their four children in Fort Worth. She handles packages for United Parcel Service, while he works construction.

But like millions of others, the coronavirus pandemic has been devastating to their finances. Once drawing an annual household income of about $56,000, the family’s earnings dwindled as Jose’s hours were cut in half and Christina now works about eight hours a week.

That’s why the relief payments Congress overwhelmingly approved in the $2 trillion Coronavirus Aid, Relief, and Economic Security (Cares) Act would mean so much to them — if only they were eligible. The law provides $1,200 to citizens with adjusted gross incomes below $75,000 and $500 per child.

Despite paying taxes, the entire family is prohibited from receiving the payments because one member, Jose, does not have a Social Security number. Christina and their children are U.S. citizens, Jose is not.

But Jose does feed government coffers using an Individual Taxpayer Identification Number (ITIN), which is available to noncitizens regardless of their legal status. It’s not clear how many families are in the same situation as the Segundo-Hernandez household, but about 4.35 million people with an ITIN paid $13.7 billion in taxes in 2015, according to an American Immigration Council report citing IRS data. They are not eligible for the same benefits as other taxpayers.

“This is a monumental injustice,” House Speaker Nancy Pelosi (D-Calif.) told reporters.

That led the Mexican American Legal Defense and Educational Fund to file a federal lawsuit against the Treasury Department on behalf of Segundo-Hernandez and others whose families cannot get coronavirus payments despite being taxpaying citizens. There is an exception in cases where one spouse is in the military.

She and others are deprived of the stimulus “just because they happen to be a mixed-status marriage where one has a Social Security number and the other has an ITIN,” said Thomas A. Saenz, the organization’s president and general counsel said in a phone interview.

When Segundo-Hernandez learned her family is not eligible for the payments, “I was upset at first and then I was angry,” she said. “I mean, what else can you feel but being upset, you can’t pay your bills. . . . You’re treated like a second-class American. You feel discriminated against just based on who you’re married to.”

The group makes that point in its brief, arguing that in denying people like Segundo-Hernandez and her children relief payments, the government “singles out one class of married individuals with social security numbers and subjects them to different treatment based on whom they marry.” When federal officials “intentionally discriminate” in this way, they violate the First Amendment and due process and equal protection provisions, the lawsuit adds.

For Robert P. Newman, the Washington lawyer who filed the suit with the defense fund, this is a fundamental question of fairness and due process. Denying citizens and their children the stimulus payment, just because they filed a joint tax return with an ITIN spouse, he said, is “a clear constitutional violation.”

The lawsuit is among others related to the fairness of the coronavirus stimulus package.

A Georgetown University Law Center lawsuit says it is unconstitutional to deny relief payments to children who are U.S. citizens because one or both parents are undocumented. Another action, filed in U.S. District Court in Chicago, says officials “have intentionally and/or recklessly punished certain United States citizens and their children from receiving the Stimulus Check for the sole reason of who they chose to marry.”

Treasury did not respond to requests for comment, but the office of Sen. Charles E. Grassley (R-Iowa), a Cares Act co-author, did.

“The bipartisan Social Security Number requirement, which was also included in the 2008 rebates, prevents illegal immigrants from qualifying for a U.S. taxpayer-funded program and helps reduce fraud and abuse,” Michael Zona, a Grassley spokesman, said in an email. “It’s based on the standards used for the earned income tax credit and the child tax credit. The importance of the Social Security Number requirement to prevent fraud is made all the more important given there is no ‘earned income’ requirement to qualify.”

Going forward, if mixed-status couples file taxes separately, which might not be in their financial interest, the one with a Social Security number could get relief payments for the family.

Unlike Democratic leaders, Grassley does not support changing the law so families with an ITIN holder can receive the relief payments. Rep. J. Luis Correa (Calif.) and other House Democrats have introduced the Leave No Taxpayer Behind Act to allow taxpayers, regardless of status, to receive relief checks.

“It's hard to believe that people would be so cruel to say that American citizens, just because of who their parent was or who they marry shouldn’t get the same rights as every other American citizen,” Senate Minority Leader Charles E. Schumer (D-N.Y.) said during a conference call organized by the Congressional Hispanic Caucus. “Senate Democrats are going to fight like hell to help ensure that all American citizens in need, regardless of the immigration status of their spouses or parents, are provided the support they need to be healthy and economically stable now and in the future.”

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