Only 36 percent of the eligible Hispanic households surveyed in California's San Joaquin Valley received the EITC they were entitled to last year — even though the credit can provide up to $4,000 for households headed by the working poor.

The disparity was evident in the partial results of the Rural Families Speak Project — a five-year survey by universities around the country into the financial well-being of rural families.

When Petra Janzer arrived at a free tax workshop, her 10-year-old car was breaking down, the tires were worn through and she had never heard of the Earned Income Tax Credit.

The $1,307 check she got last year paid for new tires and repairs, and the 56-year-old grandmother from Huron could again rely on her car to get her to her job as a child care provider 25 miles away.

Volunteers helping taxpayers in isolated rural communities say their clients' inability to access agencies that could tell them about the credit, along with language differences and cultural assumptions, often keep Hispanics from receiving the credit.

The large number of undocumented immigrants in the Hispanic population does not account for this difference, since the credit applies only to legal, working residents, with income less than twice the poverty level and at least one child living at home.

The Internal Revenue Service, recognizing the need for outreach, has trained 14,000 volunteers in the last three years to fill out the basic tax form and check for EITC eligibility. The effort has paid off. Last year, 20.9 million families got the credit — up from 16 million the year before.

Government auditors consider EITC a high-risk program, however, so this year, the IRS is asking some applicants for extra documentation proving they qualify. About 25,000 letters went out in December asking families to prove their children lived with them more than half the year.

Margarita Rocha, executive director of Centro La Familia, an advocacy organization that gives free tax help, said the letters have intimidated some recipients.

"The literacy level of our clients sometimes is not high, or they haven't been here that long," said Rocha.

EITC is often considered the most successful federal anti-poverty program. More eligible families get the EITC than traditional assistance programs like Medicaid or food stamps. In the last tax year, it gave $36.9 billion back to qualifying families.

Proponents say one of its advantages is the way it rewards only those who work. The amount each eligible taxpayer gets is equal to a percentage of income. If the earned income tax credit exceeds the taxpayer's liability, the Internal Revenue Service will refund the difference.

"These are really their dollars, not a handout," said Karen Varcoe, the University of California-Riverside consumer economics specialist who led the California research published in the January-March issue of California Agriculture magazine.

For Janzer, the EITC she never knew anything about before at Centro La Familia's free tax workshop last year means she has extra money to help care for her granddaughter. Now, it's tax time again and she's back, W-2 in hand, hoping the credit will keep her car rolling for another year.

Janzer qualified because she makes less than $24,980 per year — double the $12,490 level that marks the official beginning of poverty for a family of two.

In the Hispanic households surveyed by Varcoe and others in rural Kern and Madera counties, where unemployment is high and many workers depend on seasonal agricultural jobs, the average family income was $19,920 a year, just under poverty for a family of five. But only a third of the eligible families filed for the EITC.

"Some even have an idea that they can get money back, but they don't know how, or if they qualify," said Wilfredo Rodriguez, who works at Centro La Familia.

Knowing who is eligible is not always simple in a community where families often include citizens, undocumented immigrants and people in the process of legalizing their status. Fear of the federal government is also common.

"The IRS to them is the federales, the people who come after them," Varcoe said. But researchers found a little information about EITC goes a long way. "We're convinced that if people have information they'll act on it," Varcoe said.