How to fill out W4 correctly when I have two jobs?

Question

I have two jobs and after completing my taxes I checked my W4s. I used the IRS withholding calculator and it recommended 1 allowance for each job, since I am Single.

Each W4 for the jobs has an option that says "
Enter Additional Amount, if any, you want withheld from each paycheck:"

1. How much should I put for each job?

2. How can I calculate which amount is the best? The withholding calculator only recommends the number of allowances, but not for additional amounts.

Answer 1

Use the Two-Earners/Multiple Jobs Worksheet at the bottom of Page 2 of the W-4 Form. The amount it computes is the difference between what your employers will withhold by default and what you will owe because they are each using the wrong marginal rate. But, since it's computed on your total income, you can divide the additional amount between employers or just take it from one of the paychecks.