After you file

The applicable entry on the IRS website you reference seems to be:

"The IRS does not have my direct deposit information. What can I do?

In the coming weeks, Treasury plans to develop a web-based portal for individuals to provide their banking information to the IRS online, so that individuals can receive payments immediately as opposed to checks in the mail."

No information is provided about when or how I will be able to provide my banking information to the IRS. Why don't they just use the information the Social Security Administration already uses to send me my monthly benefit check?