"I have the paperwork and I can't tell if it is a single member or corporation."

But now you should be able to tell if there are other people involved, or not, in the LLC.

Now that you see it is Single Person, it's time to ask the IRS for a transcript or any info that helps you know if there was corporate treatment election.

"So I am going with corporation and file the business taxes. but I wanted to see if I could get a little more insight."

Whoa. This one is Easy to determine. Is she paid through Payroll? Is she using FEIN? That paperwork is available, too = applying for that FEIN. If there is FEIN, and if there is Corporation, there is payroll. That also means registered for FUTA and with your State. If none of that happened, you might be making a bad assumption for "corporation."