Holidaymakers are being warned about a little-known passport rule that could stop them from boarding a flight — even if their passport hasn’t expired.

As summer travel ramps up, many people are double-checking expiry dates and booking details before heading abroad. But there’s another important requirement travelers often overlook: blank passport pages.

For many international destinations, travelers are required to have at least one or two completely blank pages in their passport for immigration stamps and visas.

If there isn’t enough empty space available, airlines or border officials may refuse entry — and in some cases, passengers may not even be allowed to board the plane.

The issue tends to affect frequent travelers the most, especially those whose passports are packed with entry and exit stamps from previous trips.

Many people assume that if their passport is still valid, they’re safe to travel. However, immigration rules in several countries specifically require blank pages for official use.

That’s one reason why some travelers opt for larger “jumbo” passports, which include extra pages designed for people who travel regularly.

While the larger passport option usually costs slightly more, frequent flyers say it can help avoid stressful airport situations and unexpected travel disruptions.

Travel experts recommend checking passport requirements well before departure, particularly for long-haul trips or destinations with strict entry rules.

Some countries may require two consecutive blank pages, while others only need one, making it important to verify the rules for each destination before traveling.

Running out of blank pages doesn’t necessarily mean your passport is invalid as a form of ID — but it can absolutely prevent you from using it for international travel.

With airports expected to become increasingly busy over the summer period, travelers are being urged to inspect their passports carefully before heading to the airport.

Because the last thing anyone wants is for a lack of blank pages to ruin their holiday before it’s even begun.