I’ve read a lot of different things, so I’m wondering, if I have a web site and a physical location in California, do I have to now charge web site visitors a sales tax if they purchase a web site subscription service from me, for services I provide?
You will have to charge sales tax for residents in California. If you have a physical presence in any other states (like an office or warehouse), you will have to charge sales tax for the residents of those states as well.
However–this only applies for physical/tangible goods. For a digital good or service, like a digital download or subscription to access content, there’s no sales tax.
That said, I’m neither a lawyer nor an accountant, so you should check with one or both to verify that this is the case in your state and county.