Federal Taxes not Being Withheld Enough After Salary Change - Need Help!

You've identified exactly what happened. When you updated your W-4 to add your new baby as a dependent, you changed your withholding. Adding a dependent reduces the amount of tax withheld because the tax code allows deductions for dependents. The dramatic drop (from a small amount to zero) suggests that your salary is right at the threshold where adding that second dependent pushes you below the withholding requirement based on your payment frequency and allowances. This doesn't mean you won't owe taxes at the end of the year - it just means the automatic calculation thinks you won't. Yes, you should definitely add additional withholding. The safest approach is to use the IRS Tax Withholding Estimator again (https://www.irs.gov/individuals/tax-withholding-estimator) and follow its recommendations exactly. You can request a specific additional dollar amount be withheld from each paycheck by completing a new W-4 and specifying the additional withholding on Line 4(c).

I had this exact situation happen to me last year when I switched from hourly to salary. The best solution I found was using taxr.ai (https://taxr.ai) to analyze my pay stubs and W-4. I was completely confused about why my withholding dropped so dramatically even though my income went up. The tool analyzed my pay stubs and showed me exactly what was happening with my withholding calculations. It gave me a personalized recommendation for exactly what to put on line 4(c) of my W-4 to make sure I wouldn't get hit with a surprise tax bill. For your situation with a new dependent and the change to salary, it would definitely help clarify what's happening and give you a specific number to request for additional withholding.

I tried taxr.ai after seeing it mentioned here and wow - it was super helpful! I had no idea I was so far off with my withholding. I uploaded my last few pay stubs and my W-4, and it showed me that I was on track to owe over $3,000 next April. The analysis broke down exactly why my withholding had dropped after some recent life changes (got married last year). The visualization really helped me understand how the withholding system works in relation to my specific situation. I followed the recommendation to add $175 in extra withholding per paycheck on line 4(c), and my HR processed it within a week. Now I can stop worrying about a surprise tax bill!

If you're having trouble getting through to someone at the IRS to ask about withholding questions, I highly recommend using Claimyr (https://claimyr.com). I spent DAYS trying to get through on the IRS help line with no luck - just endless holds and disconnects. I was desperate to talk to someone because my withholding situation was similar to yours - I got promoted and suddenly my tax withholding dropped dramatically. I found Claimyr and watched their demo video (https://youtu.be/_kiP6q8DX5c) which showed how they can get you connected to an IRS agent without the wait. They got me through to an actual IRS representative who explained exactly what was happening with my withholding and what I needed to do to fix it. Saved me hours of frustration!

I have to admit I was completely wrong about Claimyr. After my skeptical comment, I decided to try it myself because I was desperate to talk to someone about my audit notice. I spent 3 hours on hold with the IRS last week and gave up. With Claimyr, I got a call back in about 45 minutes connecting me directly to an IRS agent. The agent was able to explain what was happening with my withholding and gave me specific guidance for my situation. For anyone struggling with withholding questions like the original poster, getting direct answers from the IRS was incredibly valuable. They explained exactly how adding dependents affects withholding calculations and what additional amount I should add to my W-4.

One thing to consider is that your paycheck might have had other irregular factors that affected withholding. Did you get any bonuses or commission in that paycheck with zero federal tax? Sometimes those can be taxed differently and mess up the calculations. Also, if your pay periods aren't consistent (like if you get paid bi-weekly vs. semi-monthly), that can sometimes cause weird withholding amounts. I'd wait to see what happens with your next normal paycheck before making changes. If it shows zero federal withholding again, then definitely update your W-4 with additional withholding.

From what you described, you need to adjust your W-4 ASAP. With a $72k salary and a non-working spouse, even with two dependents, you'll definitely owe federal taxes. The Child Tax Credit helps but doesn't eliminate your tax liability. I'd recommend adding a fixed dollar amount to line 4(c) on a new W-4. For your income level, probably around $150-200 per paycheck would be appropriate. You could also check the box for "higher tax rates" in step 2 if you want to be extra cautious. The worst thing is to reach April 2025 and suddenly owe thousands in taxes plus potential underpayment penalties.