The Internal Revenue Service has completed an audit of Vice President Mondale's 1976 federal income tax return and accepted the return as Mondale filed it, the Vice President's office announced yesterday.

Mondale's press secretary, Al Eisele, released a copy of the return and a copy of a letter, dated June 15, from the IRS to the Vice President.

The form letter, which began "Dear Taxpayer," informed Mondale that no change was required in the income and tax figures he filed with the IRS April 9.

The return showed that last year Mondale earned $44,476 in salary from the Senate and $19,358 from speaking, writing and other outside activities, and had an adjusted gross income of $62,003. The Vice President's total federal income tax obligation was $17,726, including $1,999 he owed at the time the return was filed.

Mondale claimed $10,258 in deductions, almost $7,000 of which was in state and local income and property taxes. His other deductions included $307 in charitable contributions and $150 in political contributions.

During last year's campaign, Mondale made public his tax returns for 1971 through 1975. He will continue to do so while he is Vice President, Eisele said, and, like President Carter, he endorses the IRS' plan to audit his and Carter's income tax returns for each year they are in office.

The IRS announced Monday that it has decided to audit the President's and the Vice President's tax returns each year.

The routine audit of Mondale-s taxes was apparently less extensive than the full-scale field audit the IRS is conducting of the President's 1975 income tax return. The IRS informed Carter aides in December that it planned to audit the 1975 return. White House officials, who have promised to make public the results of the audit, confirmed that the audit was taking place earlier this month after news reports that the President's 1975 return was being examined by the IRS.

Carter has not yet filed his 1976 income tax return. He received a routine two-month filing extension from the IRS in April. When the extension ran out last week, the President told reporters he had completed and filed his return.

But later the same day, White House press secretary Jody Powell said that at the last minute it was decided not to file the President's return but to obtain another 30-day extension from the IRS instead.

Calling the delay "no big deal," Powell said it resulted from someone around Carter suggesting a second look at the way part of his 1976 income was reported. The President's tax return will be made public after it is filed with the IRS, he said.