Many companies featured on Money advertise with us. Opinions are our own, but compensation and
in-depth research may determine where and how companies appear. Learn more about how we make money.

birth control pills
Laura Johansen—Getty Images

The Affordable Care Act mandates that most health insurance plans cover certain preventive care, such as flu shots and mammograms, without cost sharing—that is, no co-pays, no co-insurance, all free. “One hundred percent coverage sounds simple, but there can be complications,” says Karen Pollitz, a senior fellow at the Kaiser Family Foundation. Here’s what you need to know.

Learn the Rules

Make sure your plan is subject to the requirements; if it’s been around without substantial changes since March 23, 2010, it may not be. Ask your insurer. If the plan does require no-cost preventive care, brush up on the services you are entitled to, which include diet counseling, recommended immunizations, and cholesterol and high blood pressure screenings. You can see a full list at healthcare.gov.

Your eligibility for some services is dependent on your age and other risk factors, so ask your physician if you fit the bill for a given test or service. For example, lung cancer screening is covered for adults aged 55 to 80 who are current or former heavy smokers.

Stay In Your Network

You have to stay within your plan’s provider network to avoid co-insurance. So if you’re going in for a colonoscopy, for example, ask ahead of time to make sure the doctor performing the procedure, the facility, and any anesthesia provider are all in network, says Anna Howard, a policy development principal at the American Cancer Society Cancer Action Network (ACS CAN).

Dig Into the Details of Cancer Screening Coverage

Cancer screening has some coverage gaps. For example, some people used to wake up to a surprise fee if they had a polyp removed during a routine screening colonoscopy. For private plans, that loophole has closed. For Medicare plans, however, you are still on the hook for part of the cost if a polyp is removed, says Caroline Powers, director of federal relations for ACS CAN. Another colorectal cancer screening issue for both private plans and Medicare: If you have an annual stool-based test and blood is detected, the follow-up colonoscopy will be subject to cost-sharing even if no cancer is found, she says.

Read Next: 4 Health Moves To Make Now That Will Pay Off Later

The rules for mammograms can also be confusing. Right now some insurers count follow-up tests like an ultrasound or a biopsy as diagnostic procedures even if no cancer is found, which means you share the costs. (That may change; see below.)

Know Your Birth Control Rights

“All licensed contraceptives are supposed to be covered,” says Pollitz. But that doesn’t mean that plans can’t have a tiered formulary with preferred options, so your particular brand of pill may be subject to cost sharing. And Mara Gandal-Powers, senior counsel on the reproductive rights and health team at the National Women’s Law Center, says her organization is getting reports of coverage problems.

Some women are being incorrectly billed for related services like ultrasounds. Others are being told they’re no longer eligible for free birth control when they turn 50. And some plans have no exceptions process for making a speedy appeal when a specific type of birth control not preferred by the plan is the best one for a woman’s needs. Those things shouldn’t be happening, says Gandal-Powers. Check out coverher.org if you need help.

Stay on Top of Changes

The list of covered preventive services will be updated over time. For example, new draft recommendations for women’s preventive care would require insurers to cover tests that follow an abnormal mammogram, such as extra imaging and biopsies, without a copay.

Read Next: How To Save Lots of Money on the Health Tests You Need

The final recommendations could be out by the end of the year. If so, insurers would have to implement them by the 2018 plan year. The Kaiser Family Foundation has a helpful tracker that shows changes and federal guidance on the details.