Are 401k pre-tax salary deferrals still subject to New Jersey Unemployment, New Jersey Family Leave, and NJ SWF/WF taxes? i.e., are the 401k contributions only exempt from NJ income payroll tax and not these other NJ payroll levies.
It appears that New Jersey Unemployment tax applies to 401(k) contributions, that is, 401(k) contributions are not removed from wages to determine the NJ unemployment tax. See
"The following types of remuneration are also considered wages:... 5. Employer contributions to employees’ cash or deferred arrangements under Internal Revenue Code Section 401(k), to the extent that the employee could have elected to receive cash in lieu of making contributions." Please see https://nj.gov/labor/handbook/chap1/chap1sec4ContributionReports.html
I haven't found documentation for the other two taxes you speak of, but perhaps someone else will follow up.