EU ID Card enquiry for expiry date! no expiration date!

Hello from Greece,

I have booked some tickets for my clients and I will check in online.
Now, my problem is that in Greece the ID cards have no expiration date.
Our trip is from Rhodes to Pisa and from Pisa to Rhodes but i didnt book round trip. I booked for some of them one way to Pisa on 24/05 and one way to Rhodes back on 29/05. Could you please tell me what date i should put at the online check in as expiry date of ID card??


Thanks and wait for help asap!!

Manolis

Any date (in the future obviously ) will do, it really doesn't matter.

Is it sure??
I ask because Easyjet for istance doesn't need a specific date. I can put 10 or 15 years later after date issued.
Now Ryanair confused me a little bit...

Absolutely sure. If you're still unsure, you can call them yourself but they'll tell you the same.

Thank you so much for your help!
Greetings from Greece!