Catalyst V

Other tax discussions

Generally, yes. However, there are things that would not make it feasible in your case.

If you issued "ANY" tax reporting document (W-2, 1099-MISC) and put your SSN on that document instead of your EIN, then you're better off using the SSN on  the SCH C for 2017. Otherwise, there's a chance it could delay processing of your return, thus delaying any refund if you have one coming.

Note also that if you applied for an EIN online, that EIN can take up to 2 weeks before it's "tied" to the SSN you used when applying for it. So if you got your EIN online today, and then try to e-file with it tomorrow, chances are your e-file attempt would be rejected for "invalid EIN', as things would not have had time to propagate throughout the IRS cross-checking systems.