The debit withdrawal date will be 4/16 because banks have a cutoff time at 3pm, but the tax return will still be filed on time if filed by 11:59pm on 4/15/19.
Please see article "How to File an Amended Return with the IRS"
https://turbotax.intuit.com/tax-tips/amend-return/how-to-file-an-amended-return-with-the-irs/L...
The extension is only for filing for taxes. You still have to pay the taxes due now in order to avoid penalties. You can set up a payment plan to pay your taxes...
