Almost a quarter of the State Duma — 100 deputies — understated their incomes last year,
The research compared deputies' income declarations for 2010 and 2011 and analyzed their purchases of big-ticket items such as cars and real estate.
The head of the Duma's ethics committee, Vladimir Pekhtin, acquired a Porsche worth three times his declared income of 2.15 million rubles ($66,400).
Vladimir Pligin, head of the constitutional legislation committee, reported income of $170,000 yet sold a vintage Mercedes Benz valued at half a million dollars.
Anton Belyakov, a left-wing Just Russia deputy, bought an Infiniti jeep worth 3.8 million rubles, about twice his annual salary of 1.9 million rubles.
Duma Speaker Sergei Naryshkin, a close friend of President Vladimir Putin, declared a 5 million ruble salary and 2.7 million rubles in savings. Yet he acquired 2,500 square meters of land, a house and a 224-square meter apartment.
Former Deputy Prime Minister Boris Nemtsov recently called for the Duma to investigate how Putin, with a state salary of 3.6 million rubles, amassed a designer watch collection valued at 22 million rubles.
Yelena Panfilova, director of Transparency International Russia, stressed that no deputy was being accused of wrongdoing.
"This is not any attempt to accuse anyone of corruption," she told The Moscow Times. "The whole point of this report is to ask questions [like] 'Dear members of parliament, let us know whether you forgot to put something in or have some proper explanation [for the discrepancy].'"
Duma deputies must be reminded that the moment they decide to become public officials they fall under the scrutiny of the people, she added.
The requirement for lawmakers and top civil servants to declare their incomes was introduced by former President Dmitry Medvedev as part of his drive to curb corruption.
The Duma has the power to ask members to clarify questions about their earnings, Panfilova said.
"They simply need to ask those deputies to provide explanations because otherwise it will never be clear," she said. "Not all members of parliament and public officials understand how to do [the declaration] correctly, and inevitably there is a long way to full transparency and full accountability."
But Panfilova said this protocol has to be followed, no matter who is in the Kremlin
A spokeswoman for Pekhtin declined to comment. Reached by Vedomosti, Pekhtin said: "What, this nonsense again? The commission already checked everything long ago."
He then hung up the phone.
Belyakov told Forbes that he bought his Infiniti jeep with the proceeds from the sale of a Toyota Land Cruiser, a deal that had not been finalized when he made his 2011 declaration.
A spokeswoman for Naryshkin was not immediately available for comment. She told Vedomosti, however, that his declaration complied with the rules.
A spokeswoman for Pligin said he was unavailable for comment.
As many as 98 percent of Russians do not trust the income declarations made by senior officials and members of the government, according to a recent survey by the Levada Center, an independent pollster.