Chrysler Corp. staged a record sales performance for the second quarter of this year, but the company took a drubbing on earnings -- down 25.7 percent from the same period a year ago -- largely because of its return to taxpayer status.

Net earnings totaled $596.4 million ($5.02 a share), compared with $802.9 million ($6.48) for the same period in 1984.

Chrysler paid no taxes on last year's second-quarter profits. The company then was the beneficiary of write-offs accrued during several years of multimillion-dollar losses that almost drove it into bankruptcy in 1979.

Without taxes, Chrysler's most recent second-quarter profits would have amounted to $852 million.

"I really see no end to the black ink," said David Healy, an analyst with New York-based Drexel Burnham Lambert Inc. Healy said that Chrysler has been making steady gains in market share, partly because of favorable consumer response to its products and partly because General Motors Corp., the nation's largest auto maker, "has been in an uproar" reorganizing its operations.

Chrysler claimed 12.7 percent of the North American auto market for the first half of 1985, up from 11.5 percent for the first half of 1984. Ford Motor Co. increased its share to 21.7 percent, up from 20.6 percent over the same period. GM's North American market share dropped 2.2 percent over the period, from 46.3 percent to 44.1 percent.

GM's loss of market share through the "uproar" of reorganization and diversification was aggravated by strikes that curtailed its North American production last year, according to Healy and other analysts.

Chrysler starts bargaining with the United Auto Workers union Aug. 12 on a new labor agreement. Analysts say that if the company can complete those talks without a strike, Chrysler could finish 1985 with after-tax profits of about $1.8 billion. That would be a good showing, especially compared with earnings of $2.38 billion for 1984, during which Chrysler paid taxes for one quarter only.

Chrysler Chairman Lee A. Iacocca said yesterday that the company will use much of its new wealth to improve its product lines. One billion dollars more will be added to the company's current $10.5 billion, five-year spending program, Iacocca said.

"We think that's what we have to spend to stay competitive, to keep Chrysler strong and to protect the jobs of our employes," the Chrysler chairman said.

Chrysler had worldwide sales of $6 billion for the second quarter of 1985, which surpasses the company's previous quarterly sales record of $5.4 billion set in the first quarter of this year. Worldwide sales for the second quarter of 1984 totaled $5.3 billion.