Last year I filed for about 10 companies via Aatrix. You do have to set up each company on their system with you as a contact, but other than that there is no restrictions. If a client company later decides to access their account on Aatrix, they have to use your registration email and PW to access their account. I forget how I filed but I think I said I was a company representative, not a paid tax preparer as that required an IRS pin number which I do not have.