L1B to H1B quetion Urgent ...Please Help

[satyajit308]

I am currently working on L1B status and recently my H1 B was approved .The start date for H1B is put as January 09 2012 with COS.

My Questions are:

1. Is it Legal to work on L1B status after Jan 09^th or do it is mandatory that I must go on to payroll of H1 B employer from Jan 09^th. As I need to give a notice of 4 weeks to my Current employer and need to work on L1 B till Jan 15^th 2012.

2 My H1B employer is ok on me joining from Jan 16^th 2012.He wants me to send a letter to HR stating that I need to give 4 weeks of notice period to current company and requesting a start date of Jan 16^th. Will this create any problems while filling Green Card or after that.

Please help…