Passports: the validity you'll be asked for and the blank pages

The silliest reason for being left on the ground is a valid passport. Yes, valid: it expires in three months, it's perfectly fine at home, and the destination asks for six months of margin from the date of entry.

The months-of-margin rule

It's a very common requirement and it's counted from the date of ENTRY, or sometimes from the date you leave the country. Each destination sets the exact number of months, so it has to be checked, but the practical habit is simple: if your passport expires in less than a year, look into it before buying the ticket.

The blank pages

Some countries require free pages for the entry and exit stamps, and a few ask for two. If your passport is full of stamps and visas, this stops being an anecdote.

And not any gap counts: they want whole pages marked for visas, not the ones for endorsements.

Who checks this

Here's the detail that surprises people: the first filter is the AIRLINE, at the check-in desk. If they see you don't meet the destination's requirement, they won't let you board, because if you're sent back the cost is theirs.

So it isn't a matter of luck at the border: it's checked before you get on the plane.

Renewing in time

1. Look at the expiry date today, not in the week of the trip.
2. If you have less than twelve months left and you're travelling somewhere that needs the passport, book an appointment to renew it.
3. Expect the appointment to take weeks depending on the time of year.
4. When it arrives, update your digital copies and any electronic authorisations that were tied to the old passport.

That last point is always forgotten: many electronic authorisations are tied to the passport NUMBER, so renewing may force you to apply again.

What those authorisations are and how they work is in ESTA, eTA, ETA and the rest.