Have you checked the CA Secretary of State website to see if one was assigned to it when they registered with the SOS?

You can search by entity name here:

https://businesssearch.sos.ca.gov/

It's my understanding that if you're an LLC in CA you have a Corp number. If you don't have a Corp #, you're not an LLC in CA. 

When you file your LLC paperwork with FTB, they assign you a number.

If you didn't file your paperwork with FTB, you're not an LLC.

So, like Just-Lisa-Now says, check the California Registry. I think you can download a copy of your registration from there, though I don't do a lot of CA business, so I'm not positive.

I have the same issue. My client has the 12 digit "File Number" issued to the LLC upon formation. but not the 7 digit "Corporation" number that ProSeries wants. Discussion with CA Sec of State who told me a Corporation number would not be issued to an LLC that filed for 2553 electing to be taxed as an S-Corporation. Next call is to CA Franchise Tax Board I guess or ProSeries or enter applied for which will allow E-Filing??

I have the same issue and hoping that Proseries finds a way to resolve this. We're just going to paper file the CA-100 for the LLC but this is annoying!

That worked, thank you!

Thank you!