A Washington-area certified public accountant has been sentenced in Baltimore federal court to 90 days' in jail after pleading guilty to one count of a four-count indictment charging him with failing to file tax returns on almost $400,000 in gross income from 1976 through 1979.

U.S. District Judge Herbert F. Murray imposed a one-year jail term on Joseph A. Becker, 53, of Ellicott City, Md. The judge then suspended all but 90 days. He also ordered Becker to serve 150 hours of community service and pay all back taxes owed the federal government.

Although Becker pleaded guilty to only one count--failure to file returns on $120,402 in gross income for the year 1978--prosecutors say he owes taxes totaling $93,255 for the four-year period of the indictment on gross income of $382,789.

Becker, who now faces possible suspension or revocation of his CPA license, has already paid about $58,000 toward the back taxes, according to his attorney, Austin J. Doyle Jr. "The rest will come," Doyle said.

Doyle said Becker encountered financial difficulties during the 1976-79 period. But there was no intent to hide his earnings, Doyle said, because they were listed in corporate filings of the CPA firm in which he was partner during the period.

Becker is currently employed at the CPA firm of Frantz, Warrick, Strack & Associates in Bethesda, where Doyle says he works as "an auditor and not a tax preparer." Judge Murray specified that Becker should serve his sentence in a work-release program to permit his continued employment.