The income criteria are based on the modified adjusted gross income listed on 2013 tax forms and an estimate of this year's pay. If you guess too high on your 2014 income, you will wind up paying too much for your insurance and will get some money back when you settle up at tax time next year. If you guess too low, you may have to pay more.
"A lot of people seem to be thinking, I'm going to put my income as low as possible to get the highest credit I can and the government won't know. Yes, the government will figure it out and will adjust your tax refund next year," Ciaramitaro said.
Haile said the people who face the biggest decisions about whether to buy insurance that comes with tax credits are those near the income limits.
Say your family of four's income is $94,000, so you barely qualify for monthly credits to help with payments. Then you get an unexpected $400 bonus. "It could be the most expensive bonus you ever receive," Haile said, because it could push you over the limit for receiving credits and you may have to pay them back.
The law does set some limits on what a person must pay back if family income exceeds estimates. For example, a family at 300 percent of the federal poverty level ($71,550 for a family of four) would have to pay back a maximum of $2,500. But there is no such cap if, by the end of the year, income is over 400 percent of the poverty level.
The credits may even come into play when two people are deciding whether to get married, Haile said. If their combined incomes on a joint return put the couple over the limit, they would miss out on the monthly help with premiums they could have gotten individually.
What almost everyone agrees on is that the tax implications are complicated. That's where the navigators come in, and they are stepping up their outreach activities as time runs out to sign up.
Tim van Alstyne, a navigator with Community Counseling Centers of Chicago, said his appointments and phone consultations have been ramping up for weeks. He said there is much confusion about the penalties but he tells people that between the state's broader Medicaid options (thanks to its decision to expand the program) and the available tax credits, "no one really has to pay a penalty."
In addition to the newly allowed extension, there are other exceptions to the March 31 deadline. People experiencing life changes that affect their insurance status — such as marriage, divorce or loss of a job that provided coverage — will be able to buy a health plan later in the year. And people who qualify for Medicaid can enroll at any time.
Steve Mullen, 56, who lives in the Old Irving Park neighborhood, had been uninsured since his COBRA eligibility ran out in June. He knew he wanted to sign up for new insurance under the law, he said, but put it off until this month for financial reasons.
After meeting with Heartland Health Centers navigator Felicia Fredricks for just under an hour and a half, Mullen found a plan for himself and his wife with tax credits. He said Fredricks helped him with tax information he wouldn't have known.
"Had I not worked with Felicia, I would have made a big mistake," he said, in reference to questions about filing jointly. "I didn't realize how closely the Affordable Care Act and your tax filing status were connected."
Vivian Ezeji, another navigator for Heartland, says she's getting questions about how to project income accurately to determine tax credits when a person's pay changes from month to month. Consumers are required to report changes in pay or family size to the marketplace so credits can be adjusted, she noted.
Information on finding a navigator is available at localhelp.healthcare.gov.
A number of companies are using tax season to raise awareness about health insurance options. In addition to materials available through Jackson Hewitt, H&R Block is partnering with Chicago-based insurance portal GoHealth to help people get coverage; options are laid out at hrblock.com/healthcare. TurboTax is working with eHealthInsurance.com, a private online national exchange.
Illinois residents also can compare plans and enroll directly through HealthCare.gov.
This story was produced in partnership with Kaiser Health News, an editorially independent program of the Kaiser Family Foundation.