Hello, there! I have an LLC sole member, and I filed business/personal taxes using 1040 Schedule C. I also made estimated tax payments, to which I was just told by the IRS that by doing so, I automatically converted to a corporation and that I needed to file Form 1120, to which I am now almost 2 months delinquent, which is $195 for each month I am late. I am a bit confused - did I alter my business entity by paying quarterly taxes?

Any advice or explanation would be much appreciated! Thank you!