Is banding only possible while they are little?

Jail Bird and Beck were the only birds I've ever bought banded. Both had their bands cut off at the vet.

so, is banding bad for them in any way?

I've a cockatiel banned and a P'let... harmful I don't think so or why would it be done... its a way of tracing the original breeders...I think!

Banding parrots is a way to be able to identify them, in case if they ever get lost. Some breeders band their birds to prevent incest, because it allows them to tell them apart.

However, there are some risks, as the band could get caught on something, and that can severely injure the bird. I've rarely ever heard of these cases though, so they may not happen that often.

If you don't feel comfortable about banding your birds, it's possible to get a microchip in as well, just like one would a dog or cat. It would be able to be scanned by a vet or rescue organization to identify the bird, just like how a band would. Might be a bit more expensive though...

Dudley's the only bird in my house that currently has a band on. Because my mom bred a lot of tiels, budgies, and finches, she has a band maker.

If you want to read more into legbands, here's an article on it.
http://www.beautyofbirds.com/legbands.html

There are both pros (tracking down original breeder, identification in case if bird is lost, etc.) and cons (risk of bird being injured, or broken leg because leg band got caught), so you have to decide yourself which is more important to consider. Keep in mind that microchipping is also an option, if you want a safer alternative. However, leg bands let people know right away that the bird belongs to someone, while microchips require scanning to see if there's one there at all, and since not everyone knows about the possibility of microchipping a bird, I don't see it to be as effective all the time.

A closed band (one that is a solid ring) can only be put on while the bird is a baby. Then the bird grows bigger and the only way the band can be removed is to either cut off the band or cut off the foot.

An open band (one that has a "cut" line in it so you can spread it apart) can be put on at any time, but they're also more dangerous than a closed band because they're more prone to getting hung up on things.

Cutting off the foot wouldnt be an option would it of course cut off the band would be done.

Normally you'd cut off the band of course. But if the bird had some kind of injury that required amputation of the foot, you'd lose the band along with it.

If the closed band was too small or put on incorrectly, then chances are the foot would need to be amputated for that reason as well (like if the band severely cut off the circulation).

None of my birds were ever banded. I think it looks pretty cool (like a wrist band) but I wouldn't put it on my bird. It's not that I don't have anything against it. It's just that it sort of looks like those bands they put on some people that were in jail to track them when they are realised. Not that I have actually seen those bands, but I have heard of it. I HAVE NO CRIMINAL RECORD!! lol.