In 2019, Fred Mandelbaum, Breitling’s brand historian and a watch collector who lives in Vienna, learned the hard way about the intricacies of crossing national borders with multiple wristwatches.

“I was too late in preparing the paperwork for my personal watches for a presentation at Baselworld,” he said, referring to the now-discontinued annual trade fair. And at EuroAirport in Basel, Switzerland, customs officials found 20 vintage Breitling watches, each one 60 to 80 years old, in his carry-on shoulder bag.

“It was definitely not the cheapest way to export watches,” he said, as he was fined 12,000 Swiss francs ($13,920). “On top of that I had to pay refundable V.A.T.,” or value-added tax. (As many tourists who have bought expensive items on their European travels know, he could file a request to have the tax returned to him after his departure from Switzerland.)

Such encounters with customs have long been among watch aficionados’ favorite topics of discussion, especially now as some prepare for Watches and Wonders Geneva in April. And they got a new talking point last month when customs officials at Munich International Airport said criminal tax charges would be filed against Arnold Schwarzenegger, the movie star and former governor of California, for failing to declare a luxury wristwatch on his arrival documents.

According to local news reports, the actor said he was en route from Los Angeles to his native Austria, where the one-of-a-kind Audemars Piguet he was carrying would be auctioned at a fund-raising event. But customs rules require travelers arriving from outside the European Union to declare any goods valued at more than 430 euros ($465) that are brought into the bloc.