More than half of all the benefit cuts and individual tax increases proposed by President Reagan for fiscal 1983 would fall on households with less than $10,000 annual income, according to a Congressional Budget Office study sent to Congress yesterday.

The CBO said the average loss as a result of Reagan's proposals would be about $320 for households with income less than $10,000, about triple the figure for families earning more than $10,000.

The study, requested by Sen. Ernest F. Hollings (D-S.C.) and other members of Congress, estimated that Reagan's request for cash and in-kind benefit program cuts directly affecting individuals would total $10.8 billion in fiscal 1983 if enacted. The cuts would come largely from reductions in food stamps and Medicare, but also include housing, Medicaid, welfare, education benefits, civil service, veterans' and military benefits.

The individual tax increases, totaling $830 million, would result from Reagan's request for imposition of the federal Medicare tax on civil servants.

Of the $11.6 billion total from the cuts and tax increases, the CBO said $6.2 billion would come from households with less than $10,000 income a year; about $2.3 billion from those in the $10,000 to $20,000 category; about $2.1 billion from the $20,000 to $40,000 group, and about $950 million from those with incomes of more than $40,000.

The CBO figures show that the same general pattern would hold for 1984 and 1985 as well.

Sen. Edward M. Kennedy (D-Mass.), senior Democrat on the Senate Labor and Human Resources Committee, noted in a statement that "the harsh reality of these budget figures reveals that the Reagan budget this year, like the Reagan budget last year, takes the most from those who have the least."

The pattern of cuts falling most heavily on the lowest-income households was also true for Reagan budget cuts and tax changes enacted last year. A CBO analysis of them, released two months ago, calculated that households with incomes of less than $10,000 would suffer a net loss of more than $4.5 billion from the combined impact of benefit and tax cuts, while those with greater incomes would gain because the Reagan tax cut more than made up for any benefit losses to them.