Hi Does turbotax efile single member LLC return ( form 568)

No - TT/Calif Individual does not e-file Form 568. That must be printed out and mailed in. The printed Filing Instructions say that.

When I printed my Federal and State income tax returns the State return also printed 2019 Payment Voucher for LLC efiled Returns form 3588(efile). Did this mean that form 568 was already efiled?

You need to mail your return.

You can see if your business is supported for state efile by checking this link.

The voucher certainly makes it sound like you filed. The program is the correct answer, you need to mail.

I saw that turbo tax generated a 568 for my 2017 but 2018 didn't generate one. Why is that? 

You may need to amend your 2018 to generate a form 568. To generate a form, please follow the guidelines that is posted in this Turbo Tax link. To amend:

1. Sign in at TurboTax.com with the user ID you used when you filed your 2018 return. 
2. Select Show next to Your tax returns & documents. Select 2018
3. Select Download .tax fIle. You'll need this to amend your return.
4. Once you've got your .tax file, select 2018, and then select Amend (change) 2018 return.
5. In the expanded instructions, select download TurboTax Desktop 2018.
6. Install the TurboTax 2018 software.

• Windows instructions
• Mac instructions

1. Now open your .tax file in the TurboTax 2018 software by choosing File and then Open Tax Return (Windows) or TurboTax and then Open Tax Return (Mac). Browse to the location of your tax file and select Open.
2. You're ready to amend your 2018 return. Follow these instructions.

If you used the 2018 software, go to federal taxes>other tax situations>amend a return