It was not clear whether Sarkozy, who is manoeuvring for another run at the presidency in 2017, would be charged after the session with the magistrates in Paris.
They are investigating allegations of false accounting during his failed election campaign four years ago that allowed him to greatly exceed spending limits.
The case hinges on the activity of PR firm Bygmalion, which organised some of Sarkozy's campaign appearances and is accused of using a vast system of false accounting.
Bygmalion allegedly charged USD 21 million to Sarkozy's right-wing party -- then called the UMP, but since renamed The Republicans -- instead of billing the campaign, allowing it to greatly exceed the spending limit of USD 25 million.
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Sarkozy, 61, who led France from 2007 before losing to Socialist Francois Hollande in 2012, has always denied any knowledge of the false accounting.
He said he was retiring from politics after the election but made a comeback just two years later, returning to lead The Republicans and lining himself up for party primaries this autumn in a bid to contest the presidential election in May 2017.
Sarkozy's ambitions have not been helped by a series of scandals, including allegations that he used money from late Libyan dictator Moamer Kadhafi to fund his 2007 campaign, that he was involved in kickbacks from a Pakistani arms deal in the 1990s, and that he tried to bribe a magistrate to get inside information on yet another corruption case in which he was implicated.
His campaign director, Guillaume Lambert, has told police he warned Sarkozy of the risk of breaching financing limits.
Questioned by police in September 2015, the former president said he did not remember the warning, and described the controversy as a "farce", putting the responsibility squarely on Bygmalion and the UMP.