You should be able to do that since it is a SEP*. Its a trustee to trustee transfer. Now you want to make 200% sure the old SEP doesn't close in the process. The best way to avoid this is to do a direct partial transfer. The partial is important because that makes sure you only move 'part' of the account. I wouldn't cut it to close, don't try to get to the penny. Transfer 90% of it. That way a small market fluctuation mid transfer doesn't cause it to turn into a 100% transfer or you can do an in kind transfer based on the number of 'shares' and not dollars.
Step 1: Call Vanguard. If there is confusion about whether you can do it they can probably call State Farm with you and they will probably know which questions to ask.
* You should be able to do it since it is a SEP. You would likely not be able to do this with a SIMPLE, 403b, 401k, 457, etc. because they can only move after you leave employment.
