SAN FRANCISCO (AP) _ Convicted spy Jerry Whitworth, sentenced to 365 years in prison, may have been fined too much for additional convictions of income tax violations, federal attorneys say.

The discrepancy, which surfaced on Friday, does not affect Whitworth's prison sentence of 360 years for espionage convictions and five years for tax charges.

Whitworth was fined $100,000 for each of four false tax returns for the years 1979 through 1982, plus $10,000 for conspiring to defraud the United States. At the time Whitworth filed his returns for 1979 and 1980, however,the maximum penalty for filing a false return was $5,000.

''It appears that there may have been an inconsistency in the sentence,'' Chief Assistant U.S. Attorney William McGivern said Friday. ''We're studying what to do right now.''

The fines, imposed Thursday by U.S. District Judge John Vukasin, involve the concealment and failure to report $332,000 that Whitworth was paid by John Walker for providing Navy code and communications secrets to Walker's Soviet- controlled spy ring.

The federal tax law was amended in September 1982 to provide a maximum fine of $100,000. Whitworth's 1979 and 1980 returns were filed in April 1981.

The tax returns for 1981 and 1982 were filed in 1984, according to the indictment said.

Defense lawyers were away from their offices Friday and could not be reached for comment.