Check their web site, and any admission correspondence, through and through before contacting them.  From what I've seen, the only schools who are "prone" to letting someone do this are the ones who are "low demand," where they can save a spot for you the next time, and I would not imagine UCLA to be such a school.  But you never know.  You also should have a damn good reason.

Just ask them. There's no harm in asking.  It doesn't matter if anyone else here has or hasn't been successful at it.  Things like this are done on a case-by-case basis.

if youre going to ask you better have a very good reason to do it. they're not just going to let you defer because you want to go next year.

I asked them this at the open house. They said that you cannot defer and it is a policy of UCLA graduate division.

Rough. Thanks for your replies.