Brushaber v. Union Pacific R.R. Co
•YES!  The Supreme Court
tell us in the Brushaber decision:

“2.  The act provides for collecting the tax at the source; that is, makes it the duty of corporations, etc., to retain and pay the sum of the tax …” 
Brushaber v. Union Pacific R.R. Co, 240 US 1, 21-22 (1916).
•