When off is a preposition, the phrase off of could almost always be shortened to just off. The unnecessary of is common in informal speech and writing, though, and using it is never a serious usage error. But writers who value concision can avoid it.
Examples
For example, of could be removed from each of these sentences:
It could wean the US off of foreign oil. [State Impact]
Sarah Palin was nearly pulled off of Fox News because she announced that she was not running for president on a rival broadcaster. [Daily Mail]
In the end, the NBA, coming off of a highly lucrative and exciting season, should not suffer too much. [Toronto Sun]
He claims it has profited off of its “false affiliation” with him. [Stuff.co.nz]
I was taught that it wasn’t simply that the ‘of’ could be removed but that it must be removed. Logically if the word ‘off’ can not be replaced with ‘on’ and the phrase still work then it is just plain incorrect. e.g. If you can say “Get off of that bike” why can’t you say “Get on of that bike”?
I’ve always considered that ‘off of’ was just an abbreviation that caught on. e.g. If someone says “Get off of that Car” it was probably originally “Get off ‘the hood’ of that Car” or something similar.
What would I know? I’m silly enough to think a language should make sense.
Any thoughts on this or clarifications are most welcome.
p.s. I wasn’t particularly well educated so please excuse the many grammatical errors I probably made in this post.
“Undoctrin8ed” has it right. “Off of” is patently illogical and nonsensical. It’s monstrous — and everyone says it and writes it. Grammarist knows this but tries to compromise or find gray area where none exists. “Off of” is unqualifiedly wrong.
I always thought ‘off of’ could be used whenever ‘onto’ would work. For example: ‘Get of that bike’ / ‘Get on that bike’ and ‘Get off of the roof’ / ‘Get onto the roof’