The tax tables are meaningless to many people. I advise them to select Single, for the first submission and we will finetune it later. For two-job families, or one job and one self-employed, I advise Single and then an additional amount we determine. For W4P we figure it out by safe harbor. For W4V I advise 22% on their largest source(s), if they have multiple sources and can't put withholding on all of them (or some are so small, they don't want to lose even a bit). It's like being a short order cook.