Generally, the Other Federal Withholdings section of a tax return is used to report withholdings that are not entered elsewhere in the program. For example, taxes withheld on Form 1042-S for a taxpayer filing as a resident are entered here.
Note: A return with an amount entered in Other Federal Withholdings cannot be e-filed unless it is marked as being withheld from Form 1099. If you include an amount on this line and indicate that the withholdings are not from a 1099, the return will have to be mailed.