If I have an EIN, do I need to use it?

I don't know why you applied for an EIN, but there is really no reason for you to use it if you are not employing someone else, and then only if you withhold all taxes for that employee, and file Forms 940 and 941. In any other circumstances, there is no reason for you to use it. Check with the tax preparer who prepares you business tax documents. If you handle that yourself, i'd say you're small enough that using your SSAN will suffice.

You need to file your corporate taxes using your EIN and your personal taxes using your SSN.

Rules are slightly different in each state. Also, are you an LLC, a Class-S or a Class-C corp?

We have an EIN acquired years ago when we weren't sure what direction our business would take. We never incorporated, however, and have not used the EIN on tax returns. Now that it is just Hubby and me, we have no intention of incorporating. We use his SSN on the Schedule C though technically we both work as independent contractors.

During this period we did incorporate with partners for a different enterprise for awhile and that corporation had its own EIN. I, who had the fun job of keeping the books, did use the EIN for everything including taxes.