You know the rest. Preventive medicine aims to identify problems before they become worse, which can have a negative impact on both the patient’s finances and health.

This idea is the basis of one of the most popular components of the Affordable Care Act. It allows patients to receive certain tests and treatments without having to pay copayments or deducts.

Katie Keith, a Georgetown University researcher on the Center on Health Insurance Reforms, said that “there are still some gaps to be filled.” She said that the law made preventive care cheaper, but she disagreed.

Many patients pay nothing for routine mammograms, one of over a dozen vaccines, birth control or screenings for other conditions such as diabetes, colon cancer and depression since the ACA’s inception in late 2010.

This can lead to significant savings, especially considering that many of these tests can be expensive at thousands of dollars.

This popular provision is not without its challenges. There are ongoing Texas court cases that could overturn it. Complex and obscure qualifiers can limit its scope, leaving patients with high-priced medical bills.

KHN spoke to several experts to assist consumers in this confusing world.

Their No. Their No. If you receive a bill from a doctor, clinic or hospital, you should contact your insurance to dispute or inquire about the charges.

These are just five more things you should know:

The law covers all types of insurance, including qualified plans under the ACA consumers have purchased, job-based insurance and Medicare. Pre-ACA legacy plans that were in place before March 2010 and have not been modified since then are generally not covered. Also, most short-term and limited-benefit plans are not included. Medicare and Medicaid rules regarding who is eligible to take what tests without cost sharing can differ from those for commercial insurance. Medicare Advantage plans may offer more coverage than traditional federal programs in certain cases.

The federal government lists 22 broad categories for coverage for adults and 27 for women. There are also 29 for children.

One of the four medical expert groups must recommend vaccines, screening tests and drugs to be included on these lists. The U.S. Preventive Services Task Force is one of these advisory groups. It evaluates the potential benefits and drawbacks of screening tests in general populations.

The task force recommended that the age limit for colon cancer screening be lowered to allow people between the ages of 45 and 49. This means that more people will not have to wait until their 50th birthday in order to avoid copays and deductibles. However, older people might not be eligible if their health plans apply to the calendar year. Many do. These plans are technically only required to comply with January.

The Medicare rules in this area may differ from those of the task force, according to Anna Howard, an expert in care access at American Cancer Society Cancer Action Network. Medicare covers flexible sigmoidoscopies or stool tests for screening for colon cancer. Cost sharing is not required, and the cost of these procedures can be covered by Medicare starting at 50. Screening colonoscopies are available at any age, but they are limited to people at low risk. High-risk patients can have more frequent screenings.

Many of the recommendations from the task force are restricted to very specific populations.

The task force recommended screening for abdominal aneurysm in men between 65 and 75 years old with a history smoking.

If their doctors suspect they may have symptoms or are at high risk, all patients, including women, should be tested. These tests could then be used to diagnose rather than preventive.

Although there is some leeway in the rules for insurers, they were warned not to be too strict.

California recently punished insurers that limited cost-free testing for sexually transmitted disease to one per year. This was in violation of both state and federal laws.

There are some limitations to the ACA. Federal guidelines state that stop-smoking programs must cover counseling and medications as well as up to two quit attempts per annum.

In order to provide contraception coverage, insurers must cover at least one option in all categories of birth control without copays. However, they are not required by law to cover every contraceptive product available. Insurers could, for example, choose to concentrate on generics rather than brand-name drugs. Employers can opt out of the mandate to provide birth control.

Trouble spots appeared as the ACA entered into force. Colonoscopies were a subject of much controversy. Patients were initially charged for copayments if there were polyps. Health regulators stopped that from happening, stating that polyp removal was an essential part the screening exam. These rules are currently in effect for commercial insurance, but they are being progressively introduced for Medicare.

Federal guidance has clarified that patients can’t be charged for colonoscopies performed after suspicious results on stool-based tests. These include those sent to patients or colon examinations using CT scanners.

These rules apply to both job-based and commercial insurance, but there is one caveat. They only go into effect for policies that start in May. This means that some patients who have calendar-year coverage may not be included.

It will be “a huge win” at that point, according to Dr. Mark Fendrick of the University of Michigan’s Center for Value-Based Insurance Design.

He pointed out that Medicare is not included. He and others have urged Medicare to do the same.

These payment rules can be a problem for mammograms as well as other types of tests.

Laura Brewer, Grass Valley, California was recently compelled to go in for a mammogram in March after a cyst was discovered six months earlier in a previous exam. She was not charged for the earlier test, but she was shocked by her $1,677 bill for diagnostic procedures.

Brewer stated that they are providing the same service but changed it to be diagnostic and not screening.

Keith from Georgetown pointed out an additional complication. It may not be a specific development that causes the change, but rather a general symptom. She said that if patients have a family history or need to be tested more often, this is often coded as diagnostic.

There are dozens of vaccines that can be used for both children and adults. Certain preventive medicines are also covered, including statins for high cholesterol and certain drugs for breast-cancer. HIV-negative adults who are at high risk for getting HIV can also be covered by their insurance.

So, what’s next?

Keith stated that overall, the ACA helped reduce out-of-pocket expenses for preventive healthcare. It has been criticised, as with almost every law.

These conservatives are those who oppose some of the free services. They filed the lawsuit at a Texas federal court. If it wins, it could restrict or overturn a part of the law that does not provide cost sharing for preventive healthcare.

Kelley v. Becerra, the latest challenge to the ACA’s effectiveness — could be issued this summer. It is likely that it will be appealed.

Millions of patients could be affected if the final decision is invalidated. This includes those who have their own insurance or those who receive it through their job.

Keith stated that each insurer or employer would have to decide which preventive services they will cover and whether cost sharing is an option. Even those who do not lose access could be required to pay out of pocket for some or all preventive services.

KHN (Kaiser Health News), a national newsroom, produces in-depth journalism on health issues. KHN, along with Policy Analysis and Polling are the three main operating programs of KFF (Kaiser Family Foundation). KFF is an endowed non-profit organization that provides information to the nation on health issues.