https://ttlc.intuit.com/questions/2879424-how-do-i-print-my-4868-extension-form-after-e-filing-it-th...
If your request for an extension was accepted by the IRS, you do not do anything special now to file; the IRS knows you had an extension. However, you are now past the deadline, which was on October 17. If you tried to e-file by that deadline, you had a five day grace period in which to try to e-file again and have the return accepted as "timely."
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**