The audit was released Friday by the Federal Election Commission.
It determined that the Biden campaign accepted an illegal corporate contribution in the form of a round-trip flight between New Hampshire and Iowa in June 2007 for three people. The Biden campaign paid GEH Air Transportation $7,911 for the first-class airfare, but regulators say the campaign should have paid the charter rate of $34,800.
The FEC also found that the Biden campaign received at least $106,000 in donations that were over the limit, and the campaign was ordered to pay the U.S. Treasury more than $85,000 for stale-dated checks.
The Biden campaign also failed to disclose more than $3.7 million in payments and roughly $870,000 in debts.
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