If this is on a Sch C which is part of your personal form 1040 then that doesn't need to be fixed since is was not a required entry to start with.
The only way I can see that it would cause an issue, is when the IRS processes the return and the EIN entered does not match up with the SSN reported in the personal info section of the return. More than likely, the IRS will just fix it on their end and not bother you.
But where it could matter is this: Did you make any quarterly tax payments using your correct EIN instead of your SSN? If so, how did you make those payments? Via U.S. Mail, or online?
I make quarterly payments to comptrollers office online
Thank you both for your reply
Okay, but did you make those payments using the business EIN (and the correct one?) or your SSN? Also, your statement of "to the comptrollers office" does not sound like a payment of federal taxes to me. Sounds more like a payment of state taxes, county/city/town taxes or something like that. If so, those payment have nothing to do with your federal taxes. Federal quarterly payments are made to the IRS - not any "comptroller's office".
Hi Critter and Carl, I made the same mistake as Nellie, except I am an LLC, so wonder if your advice applies to me as well. I entered the wrong EIN # (off by one digit) on my LLC's Schedule C attached to my personal 1040. I am a single member LLC with no employees and all taxes were paid under my SSN. I only made this error on my Schedule C's (for several years) and the IRS never contacted me about the error. Does your advice hold that it doesn't need to be fixed? Should I just not enter my EIN on my next returns?