The Department of Health and Human Services is expected to recommend that Congress authorize nationwide fee schedules under which all doctors treating Medicare patients would receive the same payments for providing the same types of treatments.

The department has concluded that more study, as well as demonstration projects, are needed on two even more radical proposals for controlling doctor costs under Medicare: a prospective payment system that would provide a single payment in advance, covering all doctors' fees for each hospital patient, and a system under which HHS would contract with an insurance carrier to take over the payment of doctors under Medicare.

The department has decided that if Congress wants to overhaul the way Medicare pays doctors, the only proposal that could be put in place by the start of fiscal 1987 is the fee-schedule plan.

The latest HHS study memorandum on the subject proposes that "the department recommend movement to fee schedules which would be increasingly national in scope."

If Secretary Margaret M. Heckler approves the plan and President Reagan follows suit it would be included in his fiscal 1987 budget.

It would represent a major change in Medicare's doctor-fee system, which paid nearly $15 billion last year for the care of elderly persons and individuals covered by Social Security disability payments.

Under basic Medicare rules, physicians are reimbursed on the basis of their actual billed fees, their customary fees or the fee prevailing in the area. Doctors sometimes receive twice as much for a particular treatment as other doctors around the nation, or even in their area.

But more important, the HHS memorandum noted, is that paying doctors whatever they charge encourages them "to raise charges simply in order to secure more favorable reimbursement."

Under the fee-schedule concept, a fee would be set for each of approximately 6,000 kinds of services now specified in standard doctor billing codes. Initially, each fee would be based on the average charges within a region, but eventually the fees would be figured on a nationwide basis. Then, theoretically, any doctor performing a certain type of heart operation on a Medicare patient would get virtually the same payment, perhaps with some regional adjustment.

The HHS memorandum noted that physicians might increase the number of their treatments in order to increase their income. In that case, the memorandum said, "it appears reasonable to adjust Medicare fees downward if unexpected increases in volume take place."

The memorandum recommended that the government eventually revise the schedules to take into account the "relative value" of different services according to how much "time, skill, training and overhead" is required. Many health economists have complained that fees no longer bear much relationship to the actual skill, training and overall resources needed to perform various services, causing some treatments to be performed more frequently simply because doctors receive more money for them.

Sources said yesterday that HHS is considering awarding a major contract to Harvard University to study how to put such a relative-value scale into effect.

HHS also has studied a proposal that would set in advance a single fee for the doctor costs associated with a patient's hospital stay, based on the seriousness of the illness.

All doctors treating the patient in the hospital -- the family doctor, surgeon, anesthesiologist and others -- would share the fee. The HHS memo said it is clear that this method could control costs, but that many details need to be studied. It recommended that HHS conduct limited demonstration projects.

Demonstration projects also were recommended for the "capitation" method, under which Medicare would pay fixed annual fees to insurance companies or other groups to provide Medicare beneficiaries with all doctor services.