Is signed & accepted offer letter should be submitted for H1B petition filing


I am applying for H1B through an employer.
Is an offer letter signed by me is mandatory while filing H1B petiotion?
employer is stating that he will give offer letter after it gets picked in lotter.
is this correct?

Best Regards,

It is not a required document when submitting the application to USCIS.

However, a good employer would always share the signed offer letter before confirming the employment so that both parties know what the terms are. If the offer letter is issued after visa approval, they can change the terms like salary etc.

See if the employer can confirm to salary, benefits etc in email.

Thank you Saurabh for confirmation.