You had a return ticket, sure, but return tickets are changeable, and airline agents don’t have crystal balls. Let’s imagine that you fell so hard for Amsterdam’s rijsttafel and canal houses that you decided to stay in town for 90 days: exactly what you’re allowed to do without a visa. After one month and a few days, your passport’s expiration date would fall short of the three-month minimum. By the time you eventually came home, you’d only have one month left on your passport before it expires.

A State Department spokesman confirmed this, emailing, “Many European countries that comprise the Schengen Area require that a U.S. passport be valid for three months beyond the three-month entry visa. Some of the countries assume you may stay the full 90 days of your visa validity which is why we suggest travelers have at least six months of validity on their passports when traveling to this area.”

Another tip: Travel guidelines from official government agencies are always worth adhering to, even when couched in terms like “recommend.” Case in point: I traveled to Montreal this summer alone with my infant son and didn’t bring a parental consent letter (a notarized document stating that one parent or guardian has permission to travel alone with a minor), even though Canada “recommends” one. And sure enough, I was stopped and questioned by an immigration agent. (All good, ultimately.) With passports, much like anything airport — and final exams — related, it’s always better to prepare and prevent, rather than repair and repent.

As for the mug-shot passport photo: Aren’t they all? But yours is also a badge of honor, a reminder of the lengths you went to in order to salvage a family vacation. May the one you get in nine-and-a-half years have just as much grace and gravitas.

The Times reader Aintre recently emailed Tripped Up, asking about CLEAR lanes at airports: “How are they able to take a fee and advance passengers to the front of the TSA PreCheck line?” In fact, the two can work hand-in-hand. CLEAR uses biometrics (fingerprints and iris scans) to verify your identity; after that, PreCheck expedites the physical screening of bodies and bags.