Hey Madeline! Lovely to hear from you! Hope all is well!
We have a similar thing in the UK called National Insurance contributions for self employed, it’s probably the same everywhere. I can’t really comment as I don’t know the US system at all, but I would be very surprised if it’s much different from here. Your contributions and subscription would almost certainly be deductible against profit and you’d run at a loss, worst case scenario. That may give you a tax advantage. Guess work, of course, the US government may have something else up their sleeve!
I’m not sure about the 10% rate either, seems odd, but worth checking all of this out. I Know you used to run a business so is there anyone you can call you have a quick chat with? Or someone who is self employed who is a friend? If so, take them out for lunch and grab a notepad. I often find that people are happy to help (lunch is a bonus) and you’ll be well set up going forward.
Wish I could help more, but I would have had to have lived there for a few years first! The only thing I would definitely say is: DON’T get stressed (there are systems in place for everything), but DO get on top of it befoe it’s too late. Set a day aside this week to crack it. You will.