Kirchner, 64, filed written testimony to a court investigating her for alleged illicit association and fraudulent administration in real estate dealings.
She is suspected of favoring a construction magnate for public contracts. Her family's real estate company Los Sauces is suspected of involvement in bribes.
Hundreds of supporters rallied in her support as she arrived at the tightly guarded court to answer a summons by federal judge Claudio Bonadio.
"I am the target of judicial and media persecution which is unprecedented in this country's democracy and which also extends to my children," she said in an online message.
Bonadio on Monday had summoned Kirchner's daughter Florencia, 26, and son Maximo, 40, over their roles in Los Sauces.
Bonadio now has 10 days to decide whether to put Kirchner on trial or dismiss the case.
It is the fourth case against Kirchner to reach court since she left office in 2015, and the third in which she faces formal charges.
The case comes at a delicate time for Argentina, Latin America's third-biggest economy.
Mid-term legislative elections in October pose a key test for President Mauricio Macri, who succeeded Kirchner in December 2015.
Tens of thousands of people joined a mass demonstration in central Buenos Aires on Tuesday, the second day of a strike by teachers and hospital staff.
They are demanding pay rises and protesting job cuts and price rises under Macri's economic reforms.
"If you raise my utility costs, I will raise your political costs," read signs waved by the protesters.
Macri's Production Minister Francisco Cabrera said the protests were driven by "political motivations in an election year."
Despite the recession, he insisted the economy was creating jobs.
Union leaders at the demo called for a general strike at the start of next month.
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