17 yr old holidaying in Portugal with 18 yr Old friends

[Stopyourhavering]

I believe my ds will need some letter of authority from us as parents to allow him entry ( and exit!) to,Portugal when he holidays there post A levels in July
He's the youngest in group,and everyone else will be over 18 ( there's 12 of them staying in a villa for a week)
Who does letter need to be addressed to and is there a formal form or do we need to just sign a letter saying he's ok to go on holiday!!....he's been to Portugal with us 6 yrs ago and hadn't realised this was an issue - thank god he's told us now and not night before he flies!

Not sure about this issue specifically but just wanted to say that if the villa has been hired from someone like airbnb rather than is owned by a friend then there may be an issue with someone under 17 staying there if not accompanied by someone older - 21 or 25 seem to be the most common ages. you need to check really carefully the t's and c's for the villa if this is the case. we had this with one of my DC's group last summer and they ended up staying with family in Wales because it was just too difficult to sort out. also its likely that one of the party will have to be dominated as his responsible adult. is he planning on drinking and partying or going to just chill?

nominated not dominated oops.

Needs to be a letter from you of authorisation naming someone he is with over 18 as a person of authority. Hope this helps
www.gov.uk/foreign-travel-advice/portugal/entry-requirements