Thank you for your great question. Here is what I tell everyone. If you are owing money, the government(s) do not care if it comes from one source of income or multiple so sometimes you can just pick one source and have all the money come from that one source. For example, if you have multiple employers or retirement accounts, maybe pick only the ones you want withholdings to come out of for federal and state.
(some states do not have income taxes so disregard if you are in one of those states)
Then look at these links to learn what a W4 looks like and how to fill one out.
If you have a retirement account, then you might use a W-4 P but there are basically the same.
How to fill out a W4 Instructions on how to fill out a W4
W4 calculator Use to help fill out a W4
Form W4 Actual W4. Line 4c is where you would add extra withholdings from each check.
Once you have filled out the W-4, then in a few months maybe use the links below to do a tax estimator. This will tell you how much you might owe after making the changes. You can do a tax estimator several times per year. If you have changed your withholdings mid year, you will want to see that you keep owing less as the year goes on.
IRS Tax estimator This is a tax estimator that will time out so enter and print findings all at one sitting.
Tax caster This is another tax estimator that will time out so enter and print findings all at one sitting.
For state withholdings, it is hard to find a tax estimator for each state but they will have a state withholdings form that you can fill out.
I hope you find this information useful.
Katie S
KatherineS63