A commission check is gross pay with no withholding
A W-2 rep has income tax and half of Social Security and Medicare taken out of every check. A 1099 rep gets the full commission and owes all of it: income tax plus the 15.3% self-employment tax, paid during the year through quarterly estimates. Reps who move from W-2 to 1099 mid-year are the ones most often surprised in April.