Government agencies receive about $21.6 million in gifts from citizens and corporations each year and spend part of it for parties, receptions and extra travel expenses, according to a new report by General Accounting Office.

The report, prepared at the request of Sen. Max Baucus (D-Mont.), said there is relatively little congressional control over the way the agencies spend the money. It recommended that accounting and reporting procedures be tightened up.

Some of the gifts are given to support museums or for specific literary and scholarly undertaking. The revenues also include honoraria and travel reimbursements obtained when a government employe makes a speech paid for by some outside organization. In most cases, a honorarium may not be legally accepted by the individual employe and is turned over to his agency.

By far the biggest recipient of outside gifts in the National Endowment for the Humanities, which received more that $10 million in outside gifts and grants in fiscal 1979, according to the report.

In some cases, the National Endowment, which lacks appropriations for entertainment, will ask a donor of funds that have been given for a specified purpose whether anything left over can be used "for some other 'worthy' Endowment purpose," the GAO said.

If the donor agrees, the agency then channels the extra money into an unrestricted fund to be used for entertainment. "In effect, this worthy purpose is entertainment," the GAO said. It said that in the last three years, about $20,000 had been converted to unrestricted funds in this manner.

Channing Phillips, deputy chairman of the National Endowment, said receptions and parties are only a tiny portion of the Endowment outlays, probably no more than $35,000 a year.

Phillips also said Endowment chairman Joseph Duffey had imposed extra controls over entertainment outlays.

The GAO said the Library of Congress had used at least $33,500 for entertainment at literary meetings, receptions, exhibit openings and the like. In some cases, the gift included money not only for the costs of the exhibit but for a reception as well, as when Walt Disney Productions paid for costs of opening an animation exhibit at the Library of Congress.

The Department of Commerce spent $2,500 in 1979 to entertain auto executives. The report said at least three agencies, the National Science Foundation, Commerce Department and State Department, had paid for some travel expenses out of appropriated funds and then, when the travel was reimbursed by a private donor, had put the money into gift accounts. It said this appeared to violate rules requiring that reimbursements be used to pay off the government in cases like this. More than $25,000 was involved.

At least one agency seemed to be rolling up a big backlog of gift funds. The Naval Academy in 1979 collected $339,000 in gifts, but had $2.35 million in leftover money from previous years invested in Treasury securities and drawing interest.