youngest. Essential health benefits must be provided. The National Academy of Medicine defines the law's "essential health benefits" as "ambulatory patient services; emergency services; hospitalization; maternity and newborn care; mental health and substance use disorder services, including behavioral health treatment; prescription drugs; rehabilitative and habilitative services and devices; laboratory services; preventive and wellness services and chronic disease management; and pediatric services, including oral and vision care" and others rated Level A or B by the U.S. Preventive Services Task Force. In determining essential benefits, the law required that standard benefits should offer at least that of a "typical employer plan". States may require additional services. Preventive care and screenings for women. "[A]ll Food and Drug Administration approved contraceptive methods, sterilization procedures, and patient education and counseling for all women with reproductive capacity". This mandate applies to all employers and educational institutions except for religious organizations. These regulations were included on the recommendations of the Institute of Medicine. Annual and lifetime coverage caps on essential benefits were banned. Insurers are forbidden from dropping policyholders when they become ill. All policies must provide an annual maximum out of pocket (MOOP) payment cap for an individual's or family's medical expenses (excluding premiums). After the MOOP payment is reached, all remaining costs must be paid by the insurer. Preventive care, vaccinations and medical screenings cannot be subject to co-payments, co-insurance or deductibles. Specific examples of covered services include: mammograms and colonoscopies, wellness visits, gestational diabetes screening, HPV testing, STI counseling, HIV screening and counseling, contraceptive methods, breastfeeding support/supplies and domestic violence screening and counseling. The law established four tiers of coverage: bronze, silver, gold and platinum. All categories offer the essential health benefits. The categories vary in their division of premiums and out-of-pocket costs: bronze plans have the lowest monthly premiums and highest out-of-pocket costs, while platinum plans are the reverse. The percentages of health care costs that plans are expected to cover through premiums (as opposed to out-of-pocket costs) are, on average: 60% (bronze), 70% (silver), 80% (gold), and 90% (platinum). Insurers are required to implement an appeals process for coverage determination and claims on all new plans. Insurers must spend at least 80–85% of premium dollars on health costs; rebates must be issued if this is violated. Individual mandate The individual mandate required everyone to have insurance or pay a penalty. The mandate and limits on open enrollment were designed to avoid the insurance death spiral, minimize the free rider problem and prevent the healthcare system from succumbing to adverse selection. The mandate was intended to increase the size and diversity of the insured population, including more young and healthy participants to broaden the risk pool, spreading costs. Among the groups who were not subject to the individual mandate are: Illegal immigrants, estimated at around 8 million—or roughly a third of the 23 million projection—are ineligible for insurance subsidies and Medicaid. They remain eligible for emergency services. Medicaid-eligible citizens not enrolled in Medicaid. Citizens whose insurance coverage would cost more than 8% of household income and are exempt from the penalty. Citizens who live in states that opt out of the Medicaid expansion and who qualify for neither existing Medicaid coverage nor subsidized coverage. The Tax Cuts and Jobs Act of 2017, reduced to 0 the fine/tax for violating the individual mandate, starting in 2019. Premium subsidies Individuals whose household incomes are between 100% and 400% of the federal poverty level (FPL) are eligible to receive federal subsidies applied towards premiums for policies purchased via a PPACA exchange, provided they are not eligible for Medicare, Medicaid, the Children's Health Insurance Program, or