h1b approved can I start working or do I need the approval letter ?

Unfortunately, the company needs the H-1B approval letter before you can start working for it. The I-9 employment authorization verification form is required to be filled out by the company, and the I-797A notice of approval is a necessary document to prove your H-1B status. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.