Income to the Medicare fund is expected to be lower than estimated past year because of "lower payroll taxes attributable to lowered wages in 2017 and lower levels of projected gross domestic product", the Treasury said in a "fact sheet" accompanying the report.
A separate projection released on Tuesday showed it will become insolvent in 2034 - the same estimate as previous year.
Before the Affordable Care Act was passed, the trustees had projected the Part A trust fund would run dry this year.
Meanwhile, Medicare's hospital insurance trust fund is expected to run dry in 2026, three years earlier than what the trustees had predicted in last year's report.
Medicare spending as a percentage of gross domestic product totaled 3.7 percent in 2017, and the trustees project it will increase to at least 6.2 percent by 2092.
This year, the program's cost will outstrip total income by $2 billion and non-interest income by $85 billion, the report said. Continuing payroll tax revenues to the combined trust funds would be sufficient to cover 79 percent of scheduled benefits starting in 2034.
A major reason for Social Security's long-term financial problems is a decline in the number of workers for each beneficiary.
During 2017, 174 million people had earnings covered by Social Security and paid payroll taxes. With Social Security that could mean sharply reduced payments for retirees, many of whom are already on tight budgets.
Treasury Secretary Steven Mnuchin said the latest report shows that Social Security and Medicare remain secure, but long-term problems persist. Some combination of revenue increases and benefit changes could also eliminate the projected shortfall. The report by the trustees stressed that they've said before that the fund in trouble is not adequately financed over the next 10 years.
"The continued delay in enacting legislative repairs renders effective solutions more elusive and poses particular risks to economically vulnerable populations", Charles Blahous and Robert Reischauer, both former public trustees of the Social Security and Medicare Trust Funds, wrote in a joint report published by the Bipartisan Policy Center in advance of the trustees report.
Rather than cutting benefits, the Democratic-leaning Social Security Works coalition supports expanding benefits as a solution to the nation's looming retirement crisis by asking the wealthy to contribute more.