The IRS has not yet issued instructions for how to pay the deferred self-employment tax. (When they do provide instructions, I doubt that it will involve a payment plan.) The first payment of the deferred tax is not due until December. You're going to cause trouble and confusion if you try to make payments before the IRS provides instructions for doing so. You should hold onto the money and wait for the IRS instructions. You can set aside money each month if you want to, but keep it in your own bank account until the IRS issues the instructions for paying the deferred tax.
