Wait, I need an EIN tax number?

I talked to the IRS about my dad's taxes, and it seems that I will need to get him an EIN number, usually used for businesses, so that I can file his final return. I have to get some more research done on this, but it was not something I had expected to need. This came directly from one of the ladies on the IRS help line, though, so I will be doing more looking and share whatever I find out about that with everyone when I get that sorted out.