Typically, businesses in California must charge sales taxes on
all goods delivered in California.
If products are purchased from people out of state - and shipped to
an out of state address, you do not need to charge California sales tax.
You asked about collecting sales tax when you are selling at an out of state
a) You will not need to charge California sales tax.
b) You will have to find out about the rules for the state in which you
are making the sales. That state may have a sales tax requirement.
Often, the organizers of the event can help you get a short-term
sales tax license, just for the event.
I don't know if they still do, but I remember back in the 1960s the
State of California's sales tax folks used to prowl swap meets and find
any of the sellers who didn't have permits. They would sign them up and
have them pay for one on the spot. And instruct them to collect sales taxes.
Perhaps other states have similar arrangements?
Incidentally, I find that if you go into a local State Board of Equalization
office or call the local office directly, you're apt to get answers to your
questions. Don't call on Mondays or Friday afternoons - their lines are busy.
Best time to call? I'd say Tuesday afternoon or anytime Wednesday - at least
from my experience. Here are the phone numbers and addresses for the