Software A.G. International Inc. of Reston reported net income for its fiscal year ending May 31 of $2.3 million (50 cents a share) compared with earnings for the last fiscal year of $368,369 (8 cents). The firm is the parent company of Software A.G. of North American Inc., marketer of ADABAS and related system software products.

Revenues for the fiscal year were $18.875 million, a 74 percent increase over fiscal 1980's revenues of $10.863 million.

Expenses in fiscal 1980 included a $699,602 charge for the disposition of CAT Inc., an applications software investment.

The company's chairman and president said that the recent fiscal year's earnings "mark the beginning of an era of growth made possible by a general awareness of the need for superior system software and programming aids."

The firm made its first public offering of stock earlier this year, netting $10.650 million.

Tesdata Systems Corp. of McLean reported a net loss of $642,000 for the second quarter compared with a net loss of $27,000 in the same period in 1980. Revenue was $3.966 million, compared with $4.252 million in the second quarter of 1980.

The loss was expected, but "the amount was greater than we had anticipated," said President Robert P. Henderson

First American Bank of Virginia reported earnings for the second quarter of $3.1 million, up 34 percent from last year's second-quarter figure of $2.3 million. For the year to date, the McLean bank's net income was $6.1 million ($3.65 a share), up 36 percent from a year earlier.

Total deposits on June 30 were up 13 percent over last year, increasing to $812 million from $719 million. Total assets rose 15 percent to $944 million for the bank, which is controlled by the Financial General Bankshares Inc. holding company of Washington.

Washington Bank N.A. earned $120,650 (20 cents a share) in the second quarter of 1981 compared with a loss last year of $94,600, when the bank was called Diplomat National. Six-month net income was $206,344 (34 cents) compared with a loss of $164,815 in the 1980 period, before veteran financier Leo Bernstein purchased Washington Bank. Total deposits rose 19 percent from a year ago to $17.6 million.