This is going to be an epic fail by the IRS. The security protocols will make it unusable. The IRS has a hard enough time giving access to the data in a taxpayers account to the taxpayer, let alone trying to link an outside party to the account as well. With the password change requirements and the 2FA that will be required, it is never going to happen. In my opinion, this will last until the first taxpayer complains to their congressman about it.
Tom
Sparks, NV