Open enrollment ends March 31. (Jon Elswick/AP)

In May 2012, when the Internal Revenue Service proposed its rules for Americans to get government subsidies for health insurance, officials acknowledged that a legal quirk needed to be fixed: The Affordable Care Act was written in a way that inadvertently denied such help to some people who live apart from spouses who abuse them, are in prison or are on the cusp of a divorce.

The problem is that the law’s authors, in creating tax credits to help pay for health plans bought through the new insurance marketplaces, had overlooked the fact that some married people file their tax returns separately.

The IRS said in the preamble to those 2012 rules that it would correct the mistake, yet in the nearly two years since then, the Treasury Department has not made the change. And battered spouses have become the leading edge of a small army of people — legally married but filing taxes on their own — stepping up pressure to get an equal chance at affordable health plans.

As the first open-enrollment period for the new federal and state insurance marketplaces approaches its March 31 deadline, the Treasury Department is preparing to take steps this week to allow married survivors of domestic abuse to claim subsidies for health plans, no matter how they file their taxes, according to a department official who spoke on the condition of anonymity because the decision is not yet public. Others who are married but filing separately will not get relief for now.

A few other groups — primarily immigrants and families with twins — also have had problems enrolling, even as the sign-up period draws to a close. In these cases, their life circumstances have not meshed with the software designed for, the online insurance marketplace used in three dozen states.

The ad for features Jonah Hill, Adam Levine, Jennifer Lopez and Alicia Keys' moms. (The Washington Post)

Federal officials say that these software problems have largely been fixed, while consumer advocates say that enrollment obstacles for these groups have merely diminished. Either way, there is consensus that another hurdle looms: how to make sure that people who have been thwarted — whether for tax reasons or software ones — now sign up in time. The stakes for consumers are substantial because federal law requires most Americans to have chosen insurance by March 31 or risk a fine.

Overall enrollment in the new marketplaces is surging, reaching 5 million nationwide as of about a week ago, and the Obama administration is waging an aggressive campaign to prod more people to sign up during the enrollment period’s final week. Officials have said little, however, about specific plans for people who repeatedly tried to apply and then grew so discouraged that they stopped.

Until very recently, generated an error screen — popularly known as the “yellow screen of death” among consumer advocates familiar with it — that stopped applicants after they typed in numbers from their immigration documents to prove that they are entitled to the new insurance. Other immigrants have had trouble verifying their identities online because they lack U.S credit histories.

Parents of twins or other multiples encountered a different problem: The computer system could not handle an application if it contained more than one family member with the same birth date, so the system accepted one of the children for insurance and spit out the rest.

Treasury officials have not explained why they didn’t resolve the enrollment problems for battered women and others by Oct. 1, when enrollment in the new health plans began.

“I honestly don’t know” what to do, said a 49-year-old New York woman named Mary, who left what she described as a bad marriage 1 1 / 2 years ago and moved into a small apartment.

Mary, who asked to be identified by only her first name, said that her husband has government insurance and federal disability payments but that she has not been insured since she left a job with benefits four years ago to have more time to care for him. She is the only full-time employee of a small financial services firm. She does not get insurance and is paid slightly less than $30,000 a year — an income that would entitle her to substantial subsidies if she were not in the law’s black hole of being married but filing taxes separately.

ACA enrollment numbers, state-by-state

Mary, who has shopped repeatedly on New York’s insurance exchange, which follows the federal tax rules, has found health plans she cannot afford — ones with premiums of $300 a month and deductibles of $1,000 to $2,500. She can’t afford a divorce, which she says her husband has vowed to fight in court. Healthy in middle age, she doesn’t even want insurance, but she also doesn’t want to break the law.

“We’ve gotten ourselves into such a mess,” she said.

A Treasury spokeswoman, who spoke on the condition of anonymity about internal department discussions, said: “We take seriously the compelling rationale to allow married survivors of domestic abuse and others facing similar circumstances to claim the premium tax credit even if they are unable to file a joint income tax return.” For those other than battered spouses who will not be covered by the action this week, the department will continue to “explore ways to address the situation,” the spokeswoman said.

Meanwhile, Katie Dzurec-Dunton, who works at Maine Community Health Options, a health-care co-op in the new insurance marketplace that is helping people to sign up, said that staff noticed late last fall that if parents entered on the names of twins, the application would accept “two parents, plus the name of one twin repeated.” In the case of one family that came to the co-op with triplets, the application “dropped two of the kids.”

She and other consumer advocates say the twin problem cropped up as recently as this month. Julie Bataille, director of the Office of Communications at the Centers for Medicare and Medicaid Services, the agency that is overseeing the new insurance marketplaces, said that the twins problem was fixed earlier in the winter for people starting a new application. However, Bataille said that the twins situation remains “a retroactive problem” for families that tried to enroll before then and that the agency’s case workers are helping such people to get all family members covered.

Bataille also said that after a month of work to repair software bugs, screen errors confronting immigrant applicants have been sharply reduced, with the system now working 95 percent of the time. Part of the problem, she said, was that had trouble communicating with computers at the Department of Homeland Security to verify immigrant documents.

Jenny Rejeske, a health policy analyst at the National Immigration Law Center, said that such obstacles have lessened significantly but are “still there, and we are very, very close to the deadline.”

And some immigrants do not yet know whether solutions proposed by call center staff will work. Daniel Bourget of Gainesville, Fla., a 60-year-old naturalized citizen who arrived from Quebec 23 years ago, first tried to apply for coverage through on Oct. 1, the day that enrollment began. Bourget was laid off in 2012 from an information-technology job, and his COBRA health coverage will end in May; he needs insurance to help pay for care for his heart problems, sleep apnea and high cholesterol.

Every time Bourget typed in his immigration number and citizenship certification, the computer system’s yellow error screen would pop up. Finally, late last month, on one of his many tries to get help from a federal call center, he was told to mail in a copy of his immigration documents. He assumes that this will work but is uncertain whether they will be processed before the enrollment deadline.

“What’s hard for all of us to get our arms around is how many people still haven’t gotten through those work-arounds,” said Tricia Brooks, a senior fellow at Georgetown University’s Center for Children and Families. The government, Brooks said, should let anyone who has tried to apply for insurance, but has not succeeded, finish the application even after the enrollment deadline.

“The big question,” said Mara Youdelman, a lawyer at the National Health Law Program, “is what happens after March 31.”