If there is no deal many of the agreements within the EU will cease to apply for Britain which means UK citizens will need passports less than 10 years old and with three months validity left when they enter the EU.
It also potentially means that UK driving licenses would cease to be valid in the EU so drivers wanting to use a vehicle in the EU will have to get an International Driver Permit (IDP).
The same will apply to EU citizens wanting to visit Britain.
According to the Schengen Border Code, third country passports must have been issued within the last 10 years on the date of arrival, and have at least 3 months’ validity remaining on the date of intended departure from the last country visited in the Schengen area.
Because non-Schengen nationals can remain in the area for 90 days, passport checks may actually require at least six months’ validity on the date of arrival.
The Government’s technical notice says: “If you plan to travel to the Schengen area after 29 March 2019, to avoid any possibility of your adult British passport not complying with the Schengen Border Code we suggest that you check the issue date and make sure your passport is no older than 9 years and 6 months on the day of travel.
“If your passport does not meet these criteria, you may be denied entry to any of the Schengen area countries, and you should renew your passport before you travel.”
In a further complication, since 2001 some adult British passports have been issued with more than 10 years before they run out.
This happened in cases where passports were renewed before expiring, meaning the time left on the old travel document was added to the new one.
In such a scenario, the passport holder would not be able to use the expiry date to check if it would be valid under the new rules.
From the beginning of this month, extra validity is no longer being added to passports, with maximums now set at 10 years for adult documents and five for child passports.
Other papers included information on space debris, environmental controls, business dealings and civil law.