Here’s a fun comparison: A passport is like a carton of milk. It has a “best before” date on it, but you wouldn’t drink it the day before if you were going on a road trip. You’d want it fresh.
Similarly, a passport with 3 months left is fine for a weekend in Paris, but risky for a long-term work visa in Japan. Respect the limit, or you might be crying into your suitcase.
10-Year Rule for British Passports: Everything you need to know. - U.K
Another way to look at it: Your passport is a key. A 10-year key that fits UK locks perfectly. But some foreign doors have special timers. If the key is too old, the door won’t turn.
