This week, the government will begin assisting an estimated 20 percent of college students who get health insurance through their schools. Starting in the 2012-2013 academic year, such plans must offer an annual cap of at least $100,000, compared with the $25,000 or less that many now offer. The following year the plans must lift the cap completely.

Even better, the new rules will eliminate provisions that put strict annual limits on prescription-drug coverage or restricted coverage for outpatient treatments such as doctor visits, lab tests, emergency room visits, and chemotherapy. Under the terms of the new health-reform law, plans can’t put such caps on “essential health benefits” such as those.

“This is a big win for college students and their families,” said Aaron Smith, cofounder and executive director of Young Invincibles, a health-care advocacy group for students and young adults.

The new rules are expected to help between 1.1 million and 1.5 million students who don’t have access to insurance through their parents, or who are 26 or older and thus no longer entitled to stay on their parents’ plan.

Because the new rules won’t take effect until the school year after next, students are being advised to study the plan options carefully before signing up for the 2011-12 school year.