If you specify a direct debit date that falls on or before the mid-April filing deadline, the IRS debits your account within 1 – 4 days after your e-filed return is accepted. The actual debit date may be after the date you specified. In these cases, you won't be charged late payment penalties or interest, as long as you filed before the deadline. More info
On the other hand, if you e-file after the mid-April filing deadline, your direct debit is authorized on the date you e-filed.
Please note that it can take your bank up to five days to complete the transaction and update your account information. We suggest that you wait five days after your e-file is accepted before contacting your bank, if you are concerned that the money hasn't been debited yet.
To verify the date that funds will be withdrawn from your account, confirm that funds have been transferred, or cancel the transaction up to 48 hours before the date you designated the funds to be debited, call the IRS at 1 (888) 353-4537.
Note: Once your e-filed return has been accepted, it's no longer possible to change the bank account that will be debited.