Summary: GAO discussed the Internal Revenue Service's (IRS): (1) accounts receivable inventory from federal government agencies for employment taxes; and (2) largest accounts receivable. GAO found that: (1) for the first quarter of 1990, 676 federal entities owed $185 million in back taxes while the 98 largest receivables accounted for $6.2 billion; (2) most of the resolved amounts as of August 1990 were erroneously recorded as receivables because of IRS and taxpayer bookkeeping errors; (3) 63 federal entities owed $100,000 or more, totalling about $178 million, or about 96 percent of the amount due from all federal entities; (4) IRS penalized one-third of private employers for violating complex rules governing tax deposits in 1988; (5) two-thirds of the 63 federal agencies filed tax returns late; (6) problems stemmed from applying the same deposit and collection processes designed for private taxpayers to federal agencies; (7) as of August 1990, 74 of the 98 largest receivables still owed $3.5 billion; (8) 15 of the 98 receivables had installment or settlement agreements with IRS; and (9) the federal tax deposit system and the IRS accounting and information processing systems needed improvement to reduce erroneous receivables in the inventory.