Which one?

[cleung]

Please tell me which one is correct. Thank you.

1. I signed off your expense report already.

2. I signed off on your expense report already.

 

[riverkid]

Please tell me which one is correct. Thank you.

1. I signed off your expense report already.

2. I signed off on your expense report already.

As I envision the situation, not much context to go on, only the sentences, you're looking for #2.