How to switch job when employer doesn't give copy of i797

I have reciept number of regular processing. Now my employer has started premium processing. I don’t know if it will get processed in premium or not, but on USCIS site I get this message.

On XXX XX, 2017, we received your Form I-129, Petition for a Nonimmigrant Worker, Receipt Number XXXXXXXXX, and mailed you a receipt notice. It is being processed at our California Service Center location. The notice describes how we will process your case. Please follow the instructions in the notice. If you move, go to www.uscis.gov/addresschange to give us your new mailing address.

Based on that receipt number there alone can I switch jobs or would I need something else from my current employer?

Need more info in order to answer your question. Is this your first H-1 petition? If yes, then you need the petition be approved first before you can use it for H-1 transfer purpose.

No not the first. I came to the US last year and this year its my extention for which I have got the receipt number as above. Assuming it gets approved in the next 1-2 weeks or months, can I use just the receipt number after that to switch? I know my employer is not going to give me the approved petition or its copy.

You can switch jobs and another employer can file cap-exempt petition for you. You can submit copy of your 1st H-1 petition to show that you have already made through the cap.

If your I-94 has not expired, then no need to mention about the new extension petition. If the I-94 has expired, then you need to wait for the extension petition to be approved and submit its copy as well along w/ new I-94.

“… then you need to wait for the extension petition to be approved and submit its copy as well along w/ new I-94…”

I will not get a copy of that extension petition or the new i94. I understand both those documents will have to be given to me by my employer, which I will not get from them. All I will have is the receipt number. Now what?

Is your I-94 expired? If not, when does it expire?

It expires mid april this year.

If I-94 expires, then any transfer w/ EOS would become dependent on this pending petition. In that case wait for the extension to get approved, then use the receipt number and print out of online status showing it as approved.

As the I-94 number doesn’t change, you can still use the old number.

USCIS will be able to get the latest I-94 expiration date and petition details from their system.

I got the approval. When I go to I94 - Official Website to get my latest details it still shows my old expiry date which has already expired.

By i94 number you mean the Admission record number when I first landed in the US right?

As you have received the approval, it should have come w/ new I-94 attached to its bottom - same number, but an extended expiration date. You can use this for transfer.