Brits heading out to Portugal this summer need to make sure to check their passports before jetting off.
The western European country has a specific rule that doesn't apply to any other EU member states.
Portugal recently confirmed that UK travellers will be able to use the e-gates when heading into and leaving the country.
The decision - which is the first of its kind by an EU member - is likely to speed up the arrivals and departures process significantly.
However, Brits need to be mindful when whizzing through the e-terminals on their way back to the UK.
The UK Foreign Office has warned that all UK travellers leaving Portugal must have their passports stamped, or they face logistical difficulties later on.
The organisation's website states: "E-gates are in operation at Lisbon, Faro, Porto and Funchal (Madeira) airports for use by British and some other non-EU passport holders.
"Check your passport is stamped by the border officer when you enter and exit Portugal as a visitor.
"If relevant entry or exit stamps are not in your passport or visible to a border officer on the computer system, a border officer will may presume that you have overstayed your visa-free limit."
Passports must be stamped leaving all EU countries to show travelling Brits are abiding by the new 90-day visa free travel rules.
If you fail to get stamped then you may end up finding yourself being banned from entering Portugal in the future.
Some Brits have already fallen foul of the rule.
An elderly British woman was barred from entering Spain over a post-Brexit issue with her travel documents last year.
The woman - named only as Linda, 72 - was travelling from Gibraltar to Spain to visit her son, but was held at the border as her passport did not have an exit stamp from a previous trip.
Brits travelling in and out of the Schengen area must now have entry and exit stamps, but passport authorities forgot to stamp Linda's when she last visited the country in June.
When she attempted to visit again, she was denied entry and classed as an "overstayer".
“I was denied entry to Spain on September 26th due to my passport not being stamped on exit on a previous one-week visit to Spain which started on June 4th,” Linda told The Local.
“The guards initially stamped my passport to enter, then they noticed I had no exit stamp from that one-week visit in June, thereby classing me as an overstayer and subsequently marked the entry stamp with the letter F and two lines."
Linda said she had proof she returned to the UK, including banking activity and information from the test and trace Covid app, but claims border guards would not accept her proof - or even look at it.
She added: “My son, who speaks Spanish, tried to explain that I had other proof of returning to the UK but the guards would not accept or even consider looking at it; they just kept insisting that I had no stamp, that I had overstayed and would be arrested as illegal.”
Many travellers are also being caught out by new post-Brexit passport requirements.
The documents must not have been issued more than ten years ago and it may need up to six months left on it from the point of departure.
Portugal has followed other European countries in easing its entry requirements significantly.
Anyone who is fully vaccinated can enter mainland Portugal and the Azores without needing to test.
Those who are not jabbed need to take a PCR three days before entry or less, or an antigen in the 24 hours before departure.
