Paul Campbell3 said:My bad, I misspoke: I meant repair services, not sales. Total brain fart there. 😁
I definitely know retail and food service are off the table for this setup.
In that case, you could opt for a simplified tax filing structure. You'll just need to draft a lease agreement between the garage owner and the business entity (or if you own both the house and the garage, then an agreement between yourself and the business). That contract needs to be submitted to the IRS, among other places, so they can properly calculate the rental taxes and surcharges.
As for the actual registration process, perhaps someone else on this forum could walk through the steps? It would be great to hear from someone who has recently navigated the paperwork so you can get some firsthand insight.