If you're a UK resident planning a vacation across the pond in the next few months, you might want to check your passport. A new U.S. rule could prevent millions of British travelers from entering the country, The Telegraph reports.

The travel complications are an unintended byproduct of America's new passport rules, which went into effect on April 1. The new regulations state that anyone traveling here for business or tourism under the Visa Waiver Program (VWP) must have a valid passport with a digital biometric chip. Britain only began issuing biometric passports in October 2006, so there's still a decent chunk of citizens whose old passports have yet to reach their 10-year expiration dates. The Telegraph estimates the number of British people who were issued passports between April and October 2006 is close to 2.7 million.

No matter where in the world you live, renewing your passport is one thing you should never leave until the last minute. In the U.S. specifically, the State Department is urging citizens to take care of their expiring passports now before the surge of renewals that's expected for next year.

[h/t The Telegraph]