The statement Wednesday raises questions about whether the Trump campaign is following contribution rules, said Larry Noble, general counsel for the Campaign Legal Center and former general counsel for the Federal Election Commission.
"If she was providing speech writing services to the Trump campaign while being paid by the organization, the Trump Organization would have made, and the campaign would have accepted, an illegal contribution, unless the campaign paid the company for her speech writing services," Noble said.
McIver was not listed as a campaign employee nor did she receive money for speech writing or consulting in the Trump campaign's past Federal Election Commission filings. The campaign's June financial report is due to the FEC by midnight ET.
Trump campaign spokeswoman Hope Hicks did not immediately respond to a request for comment. The Department of Justice did not immediately respond to a request for comment.
It is legal for the Trump campaign to pay the Trump Organization for services and it has done so in the past. However, experts said the Trump campaign has blurred the lines separating it from the Trump Organization.
"The only way McIver's work could be possibly legal is if the corporation is reimbursed at a market rate. If not, this is considered a corporate contribution and is 100% illegal," said Richard Skinner, policy analyst at the Sunlight Foundation.
The FEC said it "has jurisdiction over the civil enforcement of federal campaign finance law and reviews each complaint on a case-by-case basis."
"Generally, if the Commission finds that a violation occurred, possible outcomes can range from a letter reiterating compliance obligations to a conciliation agreement, which may include a monetary civil penalty," the organization said.
— CNBC's Lori Ann LaRocco and NBC News contributed to this report.
— Update: This story has been updated to include comments from Larry Noble.