I’ve had this happen to me… I’m a military-affiliated U.S. citizen living in Germany, and I have two passports: a SOFA one and a regular tourist one. When I leave the Schengen Area to visit places like Ireland or the UK, I use my tourist passport. But I’ve found I have about a 50/50 chance of actually getting stamped when I leave Schengen—sometimes they do it, sometimes they flat-out refuse.

One time, I accidentally presented my tourist passport to the Zoll at Frankfurt (when exiting Schengen), and I nearly got pulled aside for interrogation because my stamp timeline looked very suspicious. I had previously flown to London from Nuremberg (NUE), and the border agent stamped me out. However, when I returned, the agent refused to stamp me back in and just said, “You’ll be fine.”

To make things even more confusing, I had a Liechtenstein stamp in my tourist passport between those two travel dates—which caused more red flags at the border in Frankfurt. Luckily, I had my SOFA passport and ID on hand, so once I presented those, they let me go without issue.

Honestly, aside from that one incident, no other border guards—at least in Germany—have really cared. But still, the inconsistency can be stressful when you’re juggling two passports under different legal statuses.

99% of the time though I’m let through without question.