General Electric, which had pre-tax earnings of $2.66 billion in 1981, capitalized so successfully on the bill Congress passed last year letting corporations buy and sell tax breaks that it will get a net tax refund of $90 million to $100 million from the federal government.

A second highly profitable firm that bought up tax breaks last year, Amoco, which had a pre-tax income of $3.46 billion, was able to reduce its federal liability by $159 million through tax "leasing," although the oil company did still pay several hundred million dollars in federal taxes.

These figures emerged from annual reports for 1981 that are just being released and from interviews with company officials.

GE and Amoco are generally believed to have been among the most active firms buying up tax breaks. They bought the credits and depreciation write-offs from such companies as Chrysler, Pan American, Cleveland Electric, Commonwealth Edison and Phelps Dodge.

The benefit was most dramatic in the case of GE, which went from $426 million in tax payments in 1979 and $330 million in 1980, down to its refund of $90 million to $100 million.

The company was able to achieve this negative tax situation largely through the purchase of tax credits and depreciation write-offs by a subsidiary, General Electric Credit Corp. GECC bought tax breaks from at least nine different companies and utilities through paper transactions called "leases" on about $1.4 billion worth of equipment.

The 1981 tax bill allowed companies to buy and sell tax breaks through leases; a company "leases" a piece of machinery and acquires the tax breaks associated with its cost. The provision was sold to Congress as a benefit for weaker companies. It has become highly controversial largely as a result of disclosures that profitable firms, like Occidental Petroleum, are also selling their unneeded tax breaks.

Sen. Robert J. Dole (R-Kan.), chairman of the Senate Finance Committee, has warned that he intends to seek repeal of the leasing provisions retroactive to Feb. 19.

On the surface, the GE report indicates the company was preparing to pay $529 million in federal taxes for 1981. In the more detailed notes, however, the firm pointed out that the credit company subsidiary, GECC, produced "provisions for taxes recoverable" of $633 million for 1981.

This $633 million, about one third of which resulted from buying tax benefits, was used both to reduce the 1981 tax liability and to get a refund on prior year's taxes, according to John F. McCoy, the firm's tax manager.

Although GE did not spell out the process, McCoy noted that federal law restricts the use of investment tax credits, the major first-year benefits from tax sales, so that a company can only eliminate 80 percent of its federal liability by this means.

As a result, he said, the firm had to pay 1981 taxes of between $50 million to $60 million--he would not provide precise details--but then it was able to turn around, and by virtue of the same leases, collect a refund on past years of about $150 million, for a net gain of $90 million to $100 million.

McCoy noted that "even though we have reduced our 1981 liability and have generated credits," GE's benefit was not the full amount of the tax savings because it had to pay out significant amounts of cash to buy the tax breaks.

Amoco--Standard Oil Co. (Indiana)--said directly in its annual report that "income tax expense for 1981 has been reduced by $159 million, reflecting the effect of tax benefits purchased."

The company said it expects to pay $390 million in federal taxes in 1981, compared to $433 million in 1980, although it was not clear whether the reduction resulted primarily from buying tax breaks.

Amoco did, however, note that investment tax credits for 1981 increased sharply from 1980, going from $106 million to $334 million, although no breakdown was provided to show how much of the credits resulted from investments for the firm and from purchased credits.

The effective tax rate when all state, local, foreign and federal taxes are calculated dropped from 46.7 percent in 1980 to 44.4 percent in 1981 "primarily due to higher investment tax credits associated with tax leasing arrangements," Amoco said in its report.