There is a related previous question with an answer that suggests (in passing) that the declaration can be done at the final airport before leaving the US. But it does not address whether waiting until then to declare can be seen as suspicious, or what happens if a layover is not suitably timed to do so. There is also a related previous question whose answers suggest that carrying any amount of cash on a purely US domestic flight is not in itself grounds for seizure.
This question is motivated by a news article about a US citizen who alleges that US Customs and Border Protection seized over USD 50,000 that he was carrying. The cash was discovered when he went through airport security in Cleveland for a domestic flight to Newark; his final destination was in Albania.
It brings up the issue of declaration requirements when carrying cash out of the US (although this incident may or may not have been related to the declaration issue -- the grounds and legitimacy of the forfeiture are in dispute). The man says he intended to declare the cash in Newark before boarding his international flight. Is this indeed all that is required?
It is well-known that carrying large amounts of cash in the US is risky anyway due to forfeiture practices, but is there any wrongdoing in attempting to board a domestic flight with undeclared cash over USD 10,000 that could justify its seizure by CBP? Does it matter whether the ticket includes a connection to an international flight, and whether the person is intending to carry the cash out of the country (as opposed to, e.g., giving it to someone at the domestic connecting point)?
There are also logistical issues: The CBP offices for use by departing passengers at US airports (which are not frequented or well-known by the general public, due to the lack of exit inspection in the US) are located landside, not necessarily in the passenger terminals, and not open 24/7. The information on the Newark airport office is here. What role do these logistical considerations play in when and where cash needs to be declared (e.g., whether it's even feasible to access an office during a layover)? If the originating airport doesn't even have a CBP office, then it might be necessary to travel to visit some other CBP office, potentially days before the flight.
The declaration form itself says (emphasis added):
Travelers carrying currency or other monetary instruments with them shall file FinCEN Form 105 at the time of entry into the United States or at the time of departure from the United States with the Customs officer in charge at any Customs port of entry or departure.
It's unclear whether one has to declare the money at the first stop at an airport or before leaving the United States.
Is it simply unclear to that reporter, or is it regarded as a true ambiguity by experts?
EDIT: An update regarding the case that motivated the question -- after being sued, CBP agreed to return (most of) the money (a relatively small amount is still in dispute as to how much was seized). Before this, though, according to another news article, CBP provided a statement on the case that alleged "inconsistent statements" by the man and also cited the declaration issue: "Failure to declare monetary instruments in amounts more than $10,000 can result in fines or forfeiture and could result in civil and or criminal penalties."
The layover in Newark, when he planned to declare, was apparently scheduled as four hours. His day of departure was October 24, 2017, a Tuesday; his transatlantic flight was to Frankfurt according to the lawsuit. Flights from Newark to Frankfurt typically depart in the early evening, so with a four-hour layover he might have arrived from Cleveland by about 3 pm and thus had time to visit the landside CBP office at Newark airport before it closed at 4:30 pm. (Of course flight delays can happen, and in that event he would have needed to reassess continuing his trip.)
Is any of this relevant to the declaration requirement? Can a traveler just say, in effect, "Yes, I was boarding the domestic flight without declaring; I was going to find out where to declare during my layover before leaving the US; if I successfully accomplished this, then I would board my international flight; if it didn't work out logistically for any reason (e.g., the CBP office was closed), then I would either find a way to leave the cash in the US or would cancel or postpone my onward travel until I could declare it"?