Single Member LLC California: Which forms are always required (state+federal)? Last year, TT didn't mention CA form 568 but that turned out to be a serious error.

Is it an S Corp?

It's not an S Corp.  Just SMLLC (for California)

https://ttlc.intuit.com/questions/4152993-does-turbo-tax-business-efile-ca-form-568-for-single-membe...

how can Turbo tax sell software to consumers that prepares  the forms for single member LLC,  but doesnt support e-file???? How isw one supposed to efile??? I'm reading theres a fine if one doesn't efile!!!

I feel the same.

Agreed, this is a serious oversight in TurboTax's software for State of CA small businesses.  It cost us a lot in penalties + time to fix the issue with the state.  So we switched our approach to having a tax professional + CPA review our filings from now on to spot issues like this.  I think this approach is doubly important with newer tax code changes.

I have even looked into the possibility of e-filing form 568 alone using other software or an online service and have found nothing.

If TurboTax is not able to properly file the form, I highly recommend investigating other software for your tax preparation.  Their 'work around' of filing a waiver is nonsense.

Yep, agree, its nonsense that the solution is to file a waiver. This will be my last year using Turbo tax.

Note that you must print out the 568 and mail it in - it cannot be e-filed from TT/Calif Individual. Only the TT/Business program can e-file the 568.