The generally accepted sign for "office" uses an initialized form of
the sign "box" or "room." (See: ROOM)
However, it is very common to see people spell the word
O-F-F-I-C-E.
If you are a good fingerspeller feel free to just spell office. You
should also learn the following sign so you will recognize it in case
someone uses it while chatting with you. As always, you should do this
sign however it is done by your local teacher or local Deaf community.
OFFICE:



Sample sentence:
"You have your own office?" = YOU HAVE your-SELF OFFICE?"
Also see:
BOX
Notes:
The sign OFFICE uses two hands and involves repositioning and quite
a bit of movement. Try fingerspelling the word office and
you'll see why many prefer to just fingerspell O-F-F-I-C-E. The
letters in "office" flow off the fingers very, very quickly and
smoothly thus it is literally easier (for adult native Deaf) to
spell office than it is to do the sign for OFFICE.
Also, I've got a colleague who uses (or at least he used to) a
compound of "WORK ROOM" to mean "office." He does this by
dropping one of the movements of WORK and using the non-initialized
version of room/BOX. I think it is an interesting
approach and I can certainly understand the reasoning behind doing
it that way but I'm not sure it it will catch on.