You can work for the H1B employer beyond the I-94 expiration date based on its filing of an H1B petition requesting extension of status prior to I-94 expiration. However, once your application for change of status to H4 is approved, you must discontinue employment immediately. You are not required to be employed by the H1B employer when the application to change status to H4 is filed (in case you were wondering about it). Consult with your current immigration attorney for case specific advice.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter, nor should it be viewed as establishing an attorney client relationship of any kind.
You can work on your H-1B until the change of status to H4 is approved.
Due to the nature of this forum, Attorney Maria J. Marty does not have all the information required to provide legal advice. Accordingly, her responses on Avvo are intended as general and not legal advice.