H1 start date different from appointment letter.

[question-on-H1]

I came to US on H4 in early 2005. I got my H1 (I-797) with start date in Oct '05. But my appointment letter from my employer says that my start date is Jan '06 and will start paying me from Jan'06. What is my status between Oct'05 - Dec'05? Please comment.

thanks.