The Pepper Commission, created by Congress to study health insurance problems, will recommend that the government help low-income elderly people pay Medicare charges, include more preventive services in Medicare and increase the amount that commercial policies supplementing Medicare must pay policyholders, commission sources said.

The proposals, which were endorsed by 11 of the 15 commission members Friday, would cost the government about $2.8 billion a year to implement.

The commission is headed by Sen. John D. Rockefeller IV (D-W.Va.) and named for the late congressman Claude Pepper (D-Fla.).

It proposes that the federal government, with aid from the states, pay all the Medicare outlays -- including premiums and deductibles -- for the 3.5 million people whose income is below the poverty line. That line is about $6,000 a year for an individual.

The commission also wants the government to pay a portion of those charges for the roughly 8.2 million persons whose income is between 100 percent and 200 percent of the poverty level.

Medicare is the national health care program for the elderly and disabled. The commission said Medicare premiums are $343 a year. In addition, a Medicare beneficiary must pay the first $592 for each hospital stay, added fees for the 60th to 90th days of a hospital stay, plus 20 percent of each doctor bill. A beneficiary's out-of-pocket expenses can reach thousands of dollars a year.

Under existing law, the states and the government will be required by 1992 to pay these charges for those living below the poverty line. Paying for the poor and near-poor would cost the federal government $2.6 billion a year, the commission estimated.

It would cost $200 million this year to add preventive services -- including routine mammography and colorectal and prostate screening -- to the list of services for which Medicare will pay.

The commission also will recommend that firms selling supplemental, so-called Medigap, insurance be required to pay out at least 70 percent of the amount the companies collect in premiums in the case of individual policies and 80 percent in the case of group policies. The current rules require such "loss ratios" to be 60 percent and 70 percent, respectively. Medigap policies are designed to take care of hospital and other deductibles as well as the 20 percent co-payments on doctor bills.

The commission will recommend open enrollment periods for Medigap policies during which individuals could not be denied benefits for pre-existing conditions and would be guaranteed renewability.

The 15 commission members -- 12 members of Congress and three presidential appointees -- did not hold a formal meeting. Instead the proposals were circulated to the members who signaled their position to the commission. Sources said the final tally was completed Friday.

The commission in March outlined a plan for long-term care for the elderly and suggested that all employers be required to provide policies to workers or contribute to a government backup plan for those not covered through jobs. About 31 million Americans have no health insurance.