provision for additional coverage of skilled nursing care in the indemnity insurance policies they sell or health plans they sponsor. if a beneficiary uses some portion of their part a benefit and then goes at least 60 days without receiving facility-based skilled services, the 90-day hospital clock and 100-day nursing home clock are reset and the person qualifies for new benefit periods. hospice benefits are also provided under part a of medicare for terminally ill persons with less than six months to live, as determined by the patient's physician. the terminally ill person must sign a statement that hospice care has been chosen over other medicare-covered benefits, (e.g. assisted living or hospital care). treatment provided includes pharmaceutical products for symptom control and pain relief as well as other services not otherwise covered by medicare such as grief counseling. hospice is covered 100% with no co-pay or deductible by medicare part a except that patients are responsible for a copay for outpatient drugs and respite care, if needed. part b: medical insurance part b medical insurance helps pay for some services and products not covered by part a, generally on an outpatient basis (but can also apply to acute care settings per physician designated observation status at a hospital). part b is optional. it is often deferred if the beneficiary or his/her spouse is still working and has group health coverage through that employer. there is a lifetime penalty (10% per year on the premium) imposed for not enrolling in part b when first eligible. part b coverage begins once a patient meets his or her deductible ($183 for 2017), then typically medicare covers 80% of the ruc-set rate for approved services, while the remaining 20% is the responsibility of the patient, either directly or indirectly by private group retiree or medigap insurance. part b coverage covers 100% for preventive services such as yearly mammogram screenings, osteoporosis screening, and many other preventive screenings. part b coverage includes outpatient physician services, visiting nurse, and other services such as x-rays, laboratory and diagnostic tests, influenza and pneumonia vaccinations, blood transfusions, renal dialysis, outpatient hospital procedures, limited ambulance transportation, immunosuppressive drugs for organ transplant recipients, chemotherapy, hormonal treatments such as lupron, and other outpatient medical treatments administered in a doctor's office. it also includes chiropractic care. medication administration is covered under part b if it is administered by the physician during an office visit. no prior authorization is required for any services rendered. part b also helps with durable medical equipment (dme), including but not limited to canes, walkers, lift chairs, wheelchairs, and mobility scooters for those with mobility impairments. prosthetic devices such as artificial limbs and breast prosthesis following mastectomy, as well as one pair of eyeglasses following cataract surgery, and oxygen for home use are also covered. complex rules control part b benefits, and periodically issued advisories describe coverage criteria. on the national level these advisories are issued by cms, and are known as national coverage determinations (ncd). local coverage determinations (lcd) apply within the multi-state area managed by a specific regional medicare part b contractor (which is an insurance company), and local medical review policies (lmrp) were superseded by lcds in 2003. coverage information is also located in the cms internet-only manuals (iom), the code of federal regulations (cfr), the social security act, and the federal register. the monthly premium for part b for 2019 is $135.50 per month but anyone on social security in 2019 is "held harmless" from that amount if the increase in their ss monthly benefit does not cover the increase in their part b premium from 2019 to 2020. this hold harmless provision is significant in years when ss does not increase but that is not the case for 2020. there are additional income-weighted surtaxes for those with incomes more than $85,000 per annum. part c: medicare advantage plans main article: medicare advantage with the passage of the balanced budget act of 1997, medicare beneficiaries were formally given the option to receive their original medicare benefits through capitated health insurance part c health plans, instead of through the original fee for service medicare payment system. many had previously had that option via a series of demonstration projects that dated back to the early 1970s. these part c plans were initially known in 1997 as "medicare+choice". as of the medicare modernization act of 2003, most "medicare+choice" plans were re-branded as "medicare advantage" (ma) plans (though ma is a government term and might not even be "visible" to the part c health plan beneficiary). other plan types, such as 1876 cost plans, are also available in limited areas of the country. cost plans are not medicare advantage plans and are not capitated. instead, beneficiaries keep their original medicare benefits while their sponsor administers their part a and part b benefits. the sponsor of a part c plan could be an integrated health delivery system or spin-out, a union, a religious organization, an insurance company or other type of organization. public part c medicare advantage and other part c health plans are required to offer coverage that meets or exceeds the standards set by original medicare but they do not have to cover every benefit in the same way (the plan must be actuarially equivalent to original medicare benefits). after approval by the centers for medicare and medicaid services, if a part c plan chooses to cover less than original medicare for some benefits, such as skilled nursing facility care, the savings may be passed along to consumers by offering even lower co-payments for doctor visits (or any other plus or minus aggregation approved by cms). original "fee-for-service" medicare parts a and b have a standard benefit package that covers medically necessary care as described in the sections above that members can receive from nearly any hospital or doctor in the country (if that doctor or hospital accepts medicare). original medicare beneficiaries who choose to enroll in a part c medicare advantage or other part c health plan instead give up none of their rights as an original medicare beneficiary, receive the same standard benefits—as a minimum—as provided in original medicare, and get an annual out of pocket (oop) upper spending limit not included in original medicare. however, they must typically use only a select network of providers except in emergencies or for urgent care while travelling, typically restricted to the area surrounding their legal residence (which can vary from tens to over 100 miles depending on county). most part c plans are traditional health maintenance organizations (hmos) that require the patient to have a primary care physician, though others are preferred provider organizations (which typically means the provider restrictions are not as confining as with an hmo). others are hybrids of hmo and ppo called hmo-pos (for point of service) and a few public part c health plans are actually fee-for-service hybrids. public part c medicare advantage health plan members typically also pay a monthly premium in addition to the medicare part b premium to cover items not covered by traditional medicare (parts a & b), such as the oop limit, self-administered prescription drugs, dental care, vision care, annual physicals, coverage outside the united states, and even gym or health club memberships as well as—and probably most importantly—reduce the 20% co-pays and high deductibles associated with original medicare. but in some situations the benefits are more limited (but they can never be more limited than original medicare and must always include an oop limit) and there is no premium. the oop limit can be as low as $1500 and as high as but no higher than $6700. in some cases, the sponsor even rebates part or all of the part b premium, though these types of part c plans are becoming rare. before 2003 part c plans tended to be suburban hmos tied to major nearby teaching hospitals that cost the government the same as or even 5% less on average than it cost to cover the medical needs of a comparable beneficiary on original medicare. the 2003-law payment framework/bidding/rebate formulas overcompensated some part c plan sponsors by 7 percent (2009) on average nationally compared to what original medicare beneficiaries cost per person on average nationally that year and as much as 5 percent (2016) less nationally in other years (see any recent year's medicare trustees report, table ii.b.1). the 2003 payment formulas succeeded in increasing the percentage of rural and inner-city poor that could take advantage of the oop limit and lower co-pays and deductibles—as well as the coordinated medical care—associated with part c plans. in practice, however, one set of medicare beneficiaries received more benefits than others. the medpac congressional advisory group found in one year the comparative difference for "like beneficiaries" was as high as 14% and have tended to average about 2% higher. the word "like" in the previous sentence is key. medpac does not include all beneficiaries in its comparisons and medpac will not define what it means by "like" but it apparently includes people who are only on part a, which severely skews its percentage comparisons—see january 2017 medpac meeting presentations. the differences caused by the 2003-law payment formulas were almost eliminated by ppaca and have been almost totally phased out according to the 2018 medpac annual report, march 2018. one remaining special-payment-formula program—designed primarily for unions wishing to sponsor a part c plan—is being phased out beginning in 2017. in 2013 and since, on average a part c beneficiary cost the medicare trust funds 2-5% less than a beneficiary on traditional fee for service medicare, completely reversing the situation in 2006-2009 right after implementation of the 2003 law and restoring the capitated fee vs fee for service funding balance to its original intended parity level. the intention of both the 1997 and 2003 law was that the differences between fee for service and capitated fee beneficiaries would reach parity over time and that has mostly been achieved, given that it can never literally be achieved without a major reform of medicare because the part c capitated fee in one year is based on the fee for service spending the previous year. enrollment in public part c health plans, including medicare advantage plans, grew from about 1% of total medicare enrollment in 1997 when the law was passed (the 1% representing people on pre-law demonstration programs) to about 37% in 2019. the absolute number of beneficiaries on part c has increased even more dramatically on a percentage basis because of the large increase of people on original medicare since 1997. almost all medicare beneficiaries have access to at least two public medicare part c plans; most have access to three or more. part d: prescription drug plans main articles: medicare part d and medicare part d coverage gap medicare part d went into effect on january 1, 2006. anyone with part a or b is eligible for part d, which covers mostly self-administered drugs. it was made possible by the passage of the medicare modernization act of 2003. to receive this benefit, a person with medicare must enroll in a stand-alone prescription drug plan (pdp) or public part c health plan with integrated prescription drug coverage (ma-pd). these plans are approved and regulated by the medicare program, but are actually designed and administered by various sponsors including charities, integrated health delivery systems, unions and health insurance companies; almost all these sponsors in turn use pharmacy benefit managers in the same way as they are used by sponsors of health insurance for those not on medicare. unlike original medicare (part a and b), part d coverage is not standardized (though it is highly regulated by the centers for medicare and medicaid services). plans choose which drugs they wish to cover (but must cover at least two drugs in 148 different categories and cover all or "substantially all" drugs in the following protected classes of drugs: anti-cancer; anti-psychotic; anti-convulsant, anti-depressants, immuno-suppressant, and hiv and aids drugs). the plans can also specify with cms approval at what level (or tier) they wish to cover it, and are encouraged to use step therapy. some drugs are excluded from coverage altogether and part d plans that cover excluded drugs are not allowed to pass those costs on to medicare, and plans are required to repay