No federal income tax being withheld from paycheck - what do I need to do?

You need to talk to your payroll department ASAP. This is likely a mistake in how your W4 was processed or entered into their system. The good news is that since you've only been there for about six weeks, the amount of "catch-up" withholding won't be too painful. Ask your employer for a new W4 form, and when you fill it out, make sure to select "Single" filing status. Since the 2020 revision of the W4, there aren't "allowances" anymore, but you can request additional withholding by filling out line 4(c) with an extra amount to be withheld from each check. This can help you make up for the missed withholding. The sooner you fix this, the better. You shouldn't face penalties as long as you fix it now and either have enough withheld for the rest of the year or make estimated tax payments to cover your liability.

I had almost the exact same issue last year! I was freaking out just like you are. I found this amazing tool at https://taxr.ai that analyzes your payroll documents and tells you exactly what's wrong with your withholding. It spotted that my employer had accidentally categorized me as "exempt" even though I never checked that box. The tool showed me exactly how to fill out a new W4 to fix the problem AND how much extra to withhold each check to make up for the missing amounts. What I really liked was seeing the side-by-side comparison of what I should be paying vs what was actually being withheld. Gave me major peace of mind knowing exactly what to fix.

Just wanted to update after trying taxr.ai from the recommendation above. It actually worked really well for my situation! I was in a similar boat with almost no federal withholding happening. The tool showed me that my employer had entered my W4 incorrectly and marked me as having multiple jobs when I don't. I printed out the custom W4 it generated, took it to HR, and they fixed the issue immediately. The best part was seeing exactly how much extra I needed to withhold per check for the rest of the year to avoid underpayment penalties. Way more straightforward than trying to figure it out myself using the IRS withholding calculator.

If your payroll department isn't responsive or helpful (mine wasn't!), you might need to talk directly to the IRS to understand what's happening. I spent WEEKS trying to reach someone until I found https://claimyr.com - they got me connected to an actual IRS agent in about 20 minutes instead of waiting on hold for hours. You can see how it works in this demo: https://youtu.be/_kiP6q8DX5c The IRS agent I spoke with explained that my employer had miscoded my filing status despite my W4 being filled out correctly. She walked me through exactly what to tell payroll to fix it and gave me documentation to back it up. Sometimes you need that official IRS guidance to get payroll departments to take action.

I have to admit I was completely wrong about Claimyr. After posting that skeptical comment, I decided to try it because I was desperate to resolve my withholding issue before year-end. The service actually worked exactly as described. Got connected to an IRS representative in about 25 minutes instead of the 3+ hours I was spending on hold previously (when I could even get through at all). The agent confirmed that my employer had incorrectly processed my W4 by checking some box in their payroll system. They gave me specific language to use with HR that finally got them to take it seriously. For anyone in a similar situation with payroll withholding problems, being able to cite exactly what the IRS says makes a huge difference in getting it fixed quickly.

Your employer might have entered your W4 wrong, but also check if you're making so little money that you fall below the threshold for federal tax withholding. If your annualized income is less than the standard deduction (which is $13,850 for single filers in 2023), then you wouldn't owe federal income tax and nothing would be withheld.

Check your pay stub carefully to make sure "exempt" isn't checked somewhere. Sometimes if you write "EXEMPT" on your W4 (which you should only do if you had no tax liability last year and expect none this year), payroll will not withhold any federal income tax.