Direct Pay with IRS - Already Filed

From www.irs.gov click on "Pay"

Click "Direct Pay with bank account"

Click "Pay individual tax"

Click "Make a payment"

Chose "Form 1040 - Income Tax " "Balance Due or Payment Plan" Type in the year on which you are making a payment

Click "Continue >" and the website will Verify Identity and ask for the bank routing and account information for the ACH debit.