Is client letter mandatory for H1B extension

USA Visa Stamping - US Travel
1

My H1B extension has been approved until June 1, 2028. My current H1B visa is set to expire on September 30, 2025.

During my upcoming trip to India, I will be attending my H1B extension interview. I have already scheduled appointments for both the OFC and the Consular interview (Sept-8th), and I have also opted for premium delivery of my passport and i will be back USA on sept 20th.
Except client letter i have All the necessary documents, my vendor is not providing me the client letter… without client letter can I go to interview?

Please suggest.

2

There are no set rules of book for the client letter, but in the current fricon of the immigration complexitites, its HIGHLY recommended to take all possible paperwork including the client letter.