WASHINGTON (AP) — If you haven't signed up for health insurance, you may soon be getting a not-too-subtle nudge from the taxman. The IRS is sending personalized letters to millions of taxpayers who might be uninsured, reminding them that they could be on the hook for hundreds of dollars in fines under the federal health care law if they don't sign up soon through HealthCare.gov. It's an unusual role for a revenue-collection agency. Fines are one of the most unpopular parts of the 2010 health overhaul, and there's a high likelihood they'll get repealed by Republicans, even if other parts of "Obamacare" survive. The administration is counting on IRS reminders to help sign up as many people as possible before open enrollment ends Jan. 31. That's soon after officials hand off President Barack Obama's signature program to a Trump administration committed to "repeal and replace." Letters bearing the IRS logo will be sent to an estimated 7.5 million people who either claimed an exemption from the law's requirement that most Americans carry health insurance, or who paid a penalty for being uninsured during the 2015 tax year.