WASHINGTON D.C.--Trustees of the Social Security system said yesterday a recession this year could jeopardize the system's ability to pay retirement benefits on time beginning in 1983.

The trustees also cautioned that the system's financing is still precarious even though newly-increased Social Security payroll taxes cannot be reduced unless Congress is also willing either to reduce benefits or to tap other sources of revenue.

In their annual report on the health of the insurance system, which provides benefits for retirees, survivors and the disabled, the trustees said Social Security could face problems in paying retirement benefits starting in 1983 if the nation falls into a recession this year.

The problem would clear up by 1992 because of the higher payroli taxes taking effect automatically through the 1980s, they said. The system, however, cannot afford a cut in those tax increases, enacted by Congress in 1977 to keep the system solvent.

Social Security will pay more than $101 billion to 35 million Americans this year. The trustees' report assumes that beneficiaries will get a 9.8-per-cent cost-of-living increase this July that will cost the government $10 billion.

The exact amount of the increase will not be known until April 26, when the Labor Department releases the Consumer Price Index for March.