It's a form that is filled out with specifics on how many deductions to take with specifics on how what to take them for. I figured it more as an "official form" that you aren't supposed to lie on when you submit. It doesn't ask "How many deductions would you like to take?" It asks Do you have a Spouse? Do you have a child?
So you're saying I should add an extra deduction for having a dependent even though I don't have one?
Either way I wouldn't have known, so thanks for letting me know.
Look, first you need to understand that the withholding tables are flawed to begin with. It is based of wages after withholding deductions under the presumption that you will take the standard deduction. Well, many people itemize, standard deduction is not a factor. The tables also don't take in consideration tax credits nor AMT. So, right off the bat the tables are an estimation of your annual tax based on a specific scenario.
Additionally, the IRS does not publicize that you can change your W4 at any time throughout the year. So, if you have life event (say a new baby) and don't change your W4, you are no longer using the number of household members for withholding. Simply, the W4 is a tool to help approximate your taxes by year-end. For me, this year, I probably had too many withholdings, but I've already adjusted for that. But, no, I don't have to put exact household members.