You go to the drugstore to pick up your birth control prescription and the pharmacist tells you it’s $50. Wait a second, isn’t this supposed to be free?

Well yes...and no, it turns out. The Affordable Care Act says healthcare plans must cover contraception prescribed by a woman's doctor without a copayment or coinsurance (they're considered preventative services). That means most private plans must cover the 18 methods of contraception approved by the FDA (including hormonal methods like birth control pills and vaginal rings, barrier methods like diaphragms, implanted devices, emergency contraception, and sterilization) as well as counseling appointments related to birth control.

But, as Health previously reported, insurers only have to cover one form of product in each category, which means they might only cover one type of hormonal birth control pill when there are several available, or only cover generic versions.

The thing is, there was another catch. Recent reports from the Kaiser Family Foundation and the National Women’s Law Center (NWLC) discovered that insurance companies were interpreting the law differently and denying coverage in some cases.

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“We found not all of the plans were covering every single method of birth control,” says Alina Salganicoff, Kaiser Family Foundation vice president and director of women’s health policy. Two big gaps: coverage of the hormonal ring or patch, as well as certain IUDs. “Insurers interpreted the guidance to mean if they covered a hormonal combination that was available in an oral contraceptive, they didn't have to cover the patch or ring because they were the same hormone,” she tells Health. Or, if they covered a hormonal IUD, they wouldn’t have to cover a non-hormonal version.

“Research shows that women need a wide range of choices. Contraception is not one-sized-fits-all,” Salganicoff says. In addition, “cost shouldn’t be a barrier for women to get contraception. Many of the most expensive methods are the most effective,” she says. (She’s talking about long-acting birth control, like the IUD or implants.)

In light of these issues, the Department of Health and Human Services (HHS) recently released a set of Frequently Asked Questions intended to close potential gaps in coverage. On Monday, the HHS reiterated that all 18 FDA-approved contraceptive methods for women must be covered without cost.

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"We weren’t providing enough detail about the scope of coverage provided. This seeks to eliminate any ambiguity," said Sylvia Mathews Burwell, Secretary, U.S. Department of Health and Human Services, in a conference call with reporters on Monday.

The move doesn’t change the policy—just clarifies it—but it should help more women get covered.

“This makes us very happy for women,” says Mara Gandal-Powers, council for Health and Reproductive Rights at the NWLC.

Still, that doesn’t mean your Rx will suddenly be free tomorrow. Salganicoff explains that insurers have time to phase in the guidelines, and you’ll notice this change on an employer’s plan during open enrollment, likely starting around January 2016, but college-issued plans may kick in earlier.

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Until then, if you’re still charged for birth control, you can do something about it. Gandal-Powers says the first step for women is to contact Cover Her (online or at 1-866-745-5487), which is a resource from the NWLC that teaches women about the law. “We’ll help them figure out what the issue is with their coverage,” she says. (They also have a handy list of common questions and answers, including what to do if your employer objects to coverage on religious grounds.)

For example, your plan might only cover the generic version or you may be going to an out-of-network pharmacy. The NWLC would advise you to ask your doctor for a prescription which specifies you have a medical need for the brand name or help you identify a new pharmacy, says Salganicoff. (The HHS recommends asking your doctor to contact your insurance company directly.)

But if your insurance company isn't following the law, you may need to take it a step further and appeal—a process that can be incredibly daunting. The NWLC will show you how to contact your insurer; they also have templates you can use to send an appeal letter. “We want to help women put their best foot forward in getting the coverage they need,” says Gandal-Powers.

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With additional reporting by Julie Mazziotta.