If you are filing electronically, you do not need to mail the Agreement. And you need to mail a check along with 1040-V as an initial payment if you opted for e-file. First payment will not be deducted from your bank. After your payment plan has been accepted by the IRS, since you gave them your bank information, they will debit the remaining payments on the scheduled dates. If your plan is not accepted you will have to send the remaining payments as checks.
If you file by mail you are required to send the Agreement, 1040-V and check.
