While the Office of the Chief Actuary at the government agency said it is still too early to assess the impact from Covid-19, the year-over-year change appears to reflect excess deaths. About 447,000 people who died from the virus were 65 or older, according to data from the Centers for Disease Control and Prevention, or about 80% of total deaths.

The number of Social Security beneficiaries has risen in the past decade as baby boomers -- the large cohort born between 1946 and 1964 -- started to reach retirement age. Usually, during economic downturns, many are forced into retirement due to job losses, which adds to the retiree pool.