But the filing raised more questions, not only because it had been done retroactively, but also because the person who paid the money publicly disputed that it was for the Turkish Government.
Not only did he object on Twitter, but Ekim Alptekin told the Associated Press and other news organizations that he had been pressured by Justice Department officials to make the filing this week.
Part of the work that Flynn did was an opinion piece published by the Hill newspaper on Capitol Hill, titled "Our ally Turkey is in crisis and needs our support."
The piece was dated November 8 - just hours before the votes would be counted, and Donald Trump would be elected President.
There was no notice in that piece that Flynn was behind paid for his work, which was focused on U.S.-Turkey relations.
The dates clearly show that Flynn was working as a "foreign agent" for Turkey during the final weeks of the 2016 campaign - after which he was named by the President as the next National Security Advisor.
It was not clear whether Flynn ever informed Mr. Trump about the ties to Turkey; the White House said Flynn was a "private citizen" at the time, and not subject to any work limitations.
You can read the full filing by Flynn here.