26 C.F.R. § 31.3101-3
When employee tax attaches
The employee tax attaches at the time that the wages are received by the employee. For provisions relating to the time of such receipt, see § 31.3121(a)-2.
The employee tax attaches at the time that the wages are received by the employee. For provisions relating to the time of such receipt, see § 31.3121(a)-2.