A question came from a reader:
Is it permissible for non-seminarian (male) altar servers to wear the Roman Collar whilst serving the altar? I’ve heard a lot and read a lot of conflicting reports. Besides aesthetics, MAY they wear the Collar? The lay servers at the vatican wear them and so does that that permit all altar boys?
There is a strong temptation to say "They do it at the Vatican, so we can do it here!" But it is true that the boys who serve in the sacristy at St. Peter’s Basilica do wear the Roman collar with their cassocks. But they also have the privilege of wearing the color paonazza, the violet of prelates.
Also, remember that seminarians who are not deacons are "lay servers", though we can rightly classify them more closely with the clergy.
Getting to your question… yes, I think servers can wear the Roman collar with a cassock. And the "aesthetics" is not a small reason why I say that. The squared "military" collar is just wrong without the band behind it around the throat. It is all of a piece, as it were. Another reason to wear the collar is that it helps to keep the cassocks clean and in good repair. Older servers and men should be attentive to protect the edges of the cassocks collar from being damaged against their necks.
I don’t see anything wrong with servers wearing collars, so long as they do so in the proper way. If they are using a Roman cassock for serving a Roman priest for the Roman Rite, then dress in the Roman manner.
When in Rome, as it were…