When I realized my mistake (I placed a charitable deduction twice in TT), I immediately wanted to pay the extra $35 more I owed Federal so that I don't have to pay interest and or a penalty. Because I e-filed, I have to now wait to amend my returns. My question is, will I be paying a penalty and interest on the owed $35 (on top of the already $2335 I paid via credit card while e-filing today 4-15-19)? When exactly does the IRS began charging daily interest? Does it begin April 16th, even though they haven't yet processed my e-file?