Edith Espinal at the Columbus Mennonite Church in Ohio. This week she received a letter from Immigration and Customs Enforcement that said she owed the government nearly half a million dollars.

Edith Espinal spends her days praying, reading and, when feeling brave, taking short accompanied walks outside the Mennonite church in Columbus, Ohio, where she has been living for 21 months. Church leaders have been protecting Ms. Espinal, who crossed illegally into the United States more than two decades ago, while she fights a deportation order.

But earlier this week, the church secretary handed Ms. Espinal a letter from Immigration and Customs Enforcement that said she had “willfully” refused to leave the country, had “connived or conspired” to prevent her deportation, and would owe the government nearly half a million dollars.

“We don’t have this amount of money,” Ms. Espinal, 42, said Wednesday of the $497,777 bill. “I never imagined they’d send it to us.”

Ms. Espinal was among several undocumented immigrants living in houses of worship who this week received similar notices, the latest measure taken by the Trump administration in its crackdown on illegal immigration.

Citing the Immigration and Nationality Act, ICE officials said the agency has the right to impose civil fines, up to $799 a day, on undocumented immigrants who have been ordered removed, or who have failed to leave the country. Officials said the agency began issuing such notices in December, though it was not clear on Thursday how many had been sent.

“ICE is committed to using various enforcement methods — including arrest, detention, technological monitoring and financial penalties — to enforce U.S. immigration law and maintain the integrity of legal orders issued by judges,” said Carol Danko, an agency spokeswoman.

Earlier this week, President Trump — who signed an executive order shortly after his inauguration that called on the Department of Homeland Security to collect all fines and penalties from anyone who had entered the country illegally — said that his administration would begin immigration raids after July 4.

This week’s batch of letters caught pastors and immigration activists by surprise, as houses of worship, like hospitals and schools, have generally been excluded from raids.

At St. Andrew’s Presbyterian Church in Austin, Tex., Hilda Ramirez Mendez also received a notice this week that she was under final order of removal and would be fined $303,620. She has been living for a while at the church with her 13-year-old son, whose special immigrant juvenile status application is pending. She was denied asylum in 2015, and although ICE initially allowed her to stay, her deferred action status was not extended in March, said her lawyer, Stephanie Taylor.

“The Trump administration is trying to find a way to squeeze them out of the church, which is something I’ve never heard of before,” said Ms. Taylor, who added that Ms. Ramirez does not have a criminal record. “She is terrified.”

In Charlottesville, Va., at Wesley Memorial United Methodist Church, Maria Chavalan received notice that she would be fined $214,132. She has been living at the church since September, hoping to attain asylum as a member of a protected ethnic community in Guatemala.

ImageSupporters of Ms. Espinal gathered at the church during a news conference on Wednesday.
Supporters of Ms. Espinal gathered at the church during a news conference on Wednesday.CreditMaddie McGarvey for The New York Times
The Rev. Isaac Collins, the church’s pastor, said customs officials had recently been ramping up “psychological pressure” in an attempt to force Ms. Chavalan, who does not have a criminal record and was ordered deported after missing a court date, to leave the church. Mr. Collins said Ms. Chavalan wears an ankle monitor that officials buzz late at night, and that she frequently receives calls to ask her where she is, even though she is tracked by GPS.

“The idea is to make her feel unsafe, under surveillance,” he said. “That’s what the notice of intent to fine is meant to do.”

And in North Carolina, at Chapel Hill Mennonite Fellowship, Rosa Ortez Cruz, a mother of four, received a letter that said she would be fined $314,007. Ms. Ortez Cruz, 38, is in removal proceedings after an altercation with her then-teenage son led to misdemeanor criminal charges to which she entered an Alford plea, meaning she pleaded guilty but maintained innocence, according to her lawyers. She has been living in a church since last spring.

“We are still in shock,” said the church’s pastor, Isaac Villegas.

The undocumented immigrants have 30 days to respond to the ICE letters. Lawyers and activists in about seven states, from Utah to Texas to Virginia, said they were scrambling to collaborate on a coordinated response and were working to confirm how many other migrants living in houses of worship had received notices. Across the country, more than 40 immigrants are living in houses of worship, according to Church World Service, an organization that tracks the cases.

Some lawyers said they were worried that the fines were part of a strategy by the Trump administration to target immigrant support systems. Earlier this year, a volunteer with No More Deaths, a ministry of the Unitarian Universalist Church of Tucson, faced felony charges for offering migrants water and food. The case ended in a mistrial, but federal prosecutors announced this week that they plan to retry the case in November.

Others are looking at a legal strategy that would consider the fines as the “excessive fines” prohibited by the Eighth Amendment of the Constitution.

Representative Joyce Beatty, an Ohio Democrat who represents Ms. Espinal’s area, called the fines “mean-spirited and heartless.” She said she sent letters to Mr. Trump and the Department of Homeland Security on Wednesday, asking them to rescind Ms. Espinal’s fine and allow her to stay in Columbus.

Senator Rob Portman, Republican of Ohio, said that his office had been “ensuring the facts of her case were heard by the relevant federal agencies.”

For now, the deportation case against Ms. Espinal, whose asylum claim was denied in 2017, has been appealed to the United States Court of Appeals for the Sixth Circuit in Cincinnati. When Ms. Espinal left Mexico with her father in 1995 as a teenager, she was fleeing violence and abuse, said her lawyer, Lizbeth Mateo.

“If she is removed, she will go back to a place where she is subject to abuse again; her life will be in danger,” Ms. Mateo said, adding that Ms. Espinal does not have a criminal record.

Inside Columbus Mennonite Church, Ms. Espinal, who is Roman Catholic, said she prays to the Virgin of Guadalupe, Mexico’s patron saint, for the strength and courage to keep fighting.

She said she is part of a group of women around the country living in houses of worship who check in regularly with one another, asking about their children and how they’re faring as they remain confined. Ms. Espinal says she looks forward to weekends, when her children come to spend the night and they watch movies together. Two of her three children are United States citizens, and her husband and third child also have asylum petitions pending, she said.

“We are ready to do everything we need to do to keep my family together,” she said on Wednesday, adding: “I don’t know if I can do it by myself. When the community supports me, I feel stronger.”