Looking on the internet deeply has found these results:

i am in my office is the most popular phrase on the web.

I am at my office 1272,000 results on the web	i am in my office 1335,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I am going to be in my office, if anybody needs me. I am the lawyer, Yvonne is the client, and you're the kid who gave her a lift to my office. I am also lucky that I could fit through the window in my office. Mr Duplessis, I am not calling you from my office now. And I am going to be just as rightafter breakfast up in my office. My office knows where I am, Howard. I thought I'd actually convinced them to let me stay, but... I am now officially flying to Paris to empty out my office. Usually I am, but yesterday I was in my office, working.	My office may lack a certain authority. My office is right down the street. Can I be sure that I am just as safe in my office in Parliament as I am at home? Policies that flooded my office with angry calls and letters... I am going to be in my office, if anybody needs me. Now you're ransacking my office. Can I be sure that I am just as safe in my office in Parliament as I am at home? My office has delivered over 850,000 documents.

I am at my office

1272,000 results on the web

i am in my office

1335,000 results on the web

More popular!

I am going to be in my office, if anybody needs me.
I am the lawyer, Yvonne is the client, and you're the kid who gave her a lift to my office.
I am also lucky that I could fit through the window in my office.
Mr Duplessis, I am not calling you from my office now.
And I am going to be just as rightafter breakfast up in my office.
My office knows where I am, Howard.
I thought I'd actually convinced them to let me stay, but... I am now officially flying to Paris to empty out my office.
Usually I am, but yesterday I was in my office, working.

My office may lack a certain authority.
My office is right down the street.
Can I be sure that I am just as safe in my office in Parliament as I am at home?
Policies that flooded my office with angry calls and letters...
I am going to be in my office, if anybody needs me.
Now you're ransacking my office.
Can I be sure that I am just as safe in my office in Parliament as I am at home?
My office has delivered over 850,000 documents.