Don't have health insurance? Get ready to pay up.

The ObamaCare-mandated fines for not having insurance are rising in 2015 -- and for the first time, will be collected by the Internal Revenue Service.

The individual requirement to buy health insurance went into effect earlier this year. But this coming tax season is the first time all taxpayers will have to report to the IRS whether they had health insurance for the prior year.

The fines for the 2014 year were relatively modest -- $95 per person or 1 percent of household income (above the threshold for filing taxes), whichever is more.

But insurance scofflaws face a sharp increase if they don't get covered soon. The fine will jump in 2015 to $325 or 2 percent of income, whichever is higher. By 2016, the average fine will be about $1,100, based on government figures.

The insurance requirement and penalties remain the most unpopular part of the health care law. They were intended to serve a broader purpose by nudging healthy people into the insurance pool, helping to keep premiums more affordable. But the application of fines in 2015 could renew criticism of the law, at a time when Republicans are taking control of Congress and looking at ways to undercut the policy.

According to government figures, tens of millions of people still fall into the ranks of the uninsured.

Unclear is how many would actually be assessed a fine. The law offers about 30 different exemptions, most of which involve financial hardships. Further, it's unclear how aggressively the IRS would go after the fines.

Many taxpayers may be able to get a pass.

Based on congressional analysis, tax preparation giant H&R Block says roughly 4 million uninsured people will pay penalties and 26 million will qualify for exemptions from the list of waivers.

Deciding what kind of waiver to seek could be crucial. Some can be claimed directly on a tax return, but others involve mailing paperwork to the Department of Health and Human Services. Tax preparation companies say the IRS has told them it's taking steps to make sure taxpayers' returns don't languish in bureaucratic limbo while HHS rules on their waivers.

TurboTax has created a free online tool called "Exemption Check" for people to see if they may qualify for a waiver. Charges apply later if the taxpayer files through TurboTax. People also can get a sense of the potential hit by going online and using the Tax Policy Center's Affordable Care Act penalty calculator.

Timing also will be critical for uninsured people who want to avoid the rising penalties for 2015.

That's because Feb. 15 is the last day of open enrollment under the health law. After that, only people with special circumstances can sign up. But just 5 percent of uninsured people know the correct deadline, according to a Kaiser Family Foundation poll.

"We could be looking at a real train wreck after Feb. 15," said Stan Dorn, a health policy expert at the nonpartisan Urban Institute. "People will file their tax returns and learn they are subject to a much larger penalty for 2015, and they can do absolutely nothing to avoid that."

In a decision that allowed Obama's law to advance, the Supreme Court ruled in 2012 that the coverage requirement and its accompanying fines were a constitutionally valid exercise of Congress' authority to tax.

Sensitive to political backlash, supporters of the health care law have played down the penalties in their sign-up campaigns. But stressing the positive -- such as the availability of financial help and the fact that insurers can no longer turn away people with health problems -- may be contributing to the information gap about the penalties.

The Associated Press contributed to this report.