What did you find out from your research?  If you tell us, someone may just validate it for you or point you in the right direction.

Thanks @itonewbie May it was stupid question but for mailing paper I do know where the address of IRS would be but for E-filing I did not find the address.

As you know, 83(b) should mail the IRS's address which their tax return will go.

No one inferred it's a stupid question.  You were a teacher.  I'm sure you would have preferred (if not expected) your students to attempt to reason and answer their own questions beforehand.  That's the best way for someone to learn.

Furthermore, we volunteer here to share experience and learn from one another but that doesn't mean doing someone else's research.  I'm sure you understand.

Your client will just file with the same IRS office where a paper return would have gone.  §1.83-2(c) does not prescribe a different process for e-filers.

@itonewbie I wanted to take a moment to express my sincere gratitude. Your consistently respectful and thoughtful response to my questions have not gone unnoticed. your support means a lot to me. 

NP, @HOPE2.  Glad to be of help. 🙂

@George4Tacks I really appreciated it! it was very helpful.