Which documents are accepted for border-free Schengen EU countries?
If you are an EU national, you do not need to show your national ID card or passport when you are travelling from one border-free Schengen EU country to another.
Even if you don’t need a passport for border checks within the Schengen area, it is still always highly recommended to take a passport or ID card with you, so you can prove your identity if needed (if stopped by police, boarding a plane, etc.). Schengen EU countries have the possibility of adopting national rules obliging you to hold or carry papers and documents when you are present on their territory.
Driving licences, post, bank or tax cards are not accepted as valid travel documents or proof of identity.