For international trips I have a passport, for EU journeys I use my national identity card. Simply because its format is more convenient, since it fits in my wallet. On my next trip to the UK my national identity card will only be valid for only one week when I return. I am aware of validity issues on passports (e.g. your passport needs to be at least valid for more then 6 months when traveling to the US), what are the regulations regarding national identity cards in the EU? Can I use it to travel within the EU until the last day of its validity?
According to the UK Border Agency, all you need is a valid EU national ID card, no mentioning of validity:
When you enter the UK, you must show your passport or national identity card. You should use the separate channel marked 'EEA/EU', where it is available. Immigration officers will check your passport or national identity card to ensure that it is valid and belongs to you.
Also, according to another document issued by the same agency:
Regulation 11(4) states that when an EEA national does not produce on arrival a valid ID card or passport he should be given “every reasonable opportunity” to prove by other means that he is an EEA national. In other words a person claiming to be an EEA national should not automatically be refused admission as a result of being unable to produce a valid ID card or passport.
I could not find any official source where it says a certain period of validity is required for EU/EEA nationals when presenting their national ID cards. Therefore I guess you can use your valid ID card even if it is valid for one more day.