The Home Office will send around one million text messages to passport holders who may need to renew their passports early.
New passport validity rules will apply for travel to most European countries in a no deal Brexit.
The text messages will encourage people to check if their passport will meet these new rules to help them with any plans for travel to Europe after 31 October.
There are 2 new rules that passports will need to meet to travel to most countries in Europe.
Firstly, travellers will need to have at least 6 months left on their passport.
Secondly, any extra months on a passport over 10 years may not count towards the 6 months needed. A passport may have extra months if the holder renewed their previous passport before it expired.
The texts will be sent to those who provided their mobile number when they applied for their current passport.
Not everyone provides a mobile number, and