Washington (CNN Politics) President Donald Trump's company donated more than half a million dollars to the Donald J. Trump Foundation last year, according to a 2017 tax return made available Monday.

The purpose of $502,400 contribution from the Trump Corp. to the foundation was not disclosed in the filings.

The New York state attorney general has accused the foundation in a civil lawsuit of "repeated and willful self-dealing transactions" that violate state and federal charity laws. A judge ruled Friday that the suit, which seeks $2.8 million in restitution and additional penalties, can proceed even with Trump in the White House.

Marcus Owens, a former director of the nonprofits division at the IRS, said it was impossible to know the purpose of the Trump Corp. donation from the filing, which does not disclose the date of the receipt.

"This contribution could be part of the foundation trying to get right with the IRS or state of New York," said Owens.

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