I submitted form 4868 electronically. Can I submit a payment after already filing the form

[IRonMaN]

Not through the software.

[mjguynes]

Thanks. I didn't think you could. 

[PATAX]

@mjguynes @IRonMaN Iron Man Is right... You may be able to make this payment through EFTPS... But you have to register first and then obtain a PIN which I think they mail to you...

[dkh]

You could use IRS Direct Pay - however, you can't select an extension payment since it's past 05/17.  You'd have to select Balance Due.   Better to do that than wait and have more penalties/interest.