Why am I owing so much on taxes with W-4 set to Single 0 withholding? Help!

Thanks for the response! I had no idea they changed the W-4 system. That explains so much. So basically when I told HR "single 0" they probably just checked the "single" box on the new form without any additional withholding? Also, does this mean I should expect to owe again next year unless I update my W-4? And roughly how much extra should I have withheld per paycheck to cover that $5,300 gap?

Yes, that's likely what happened. When you said "single 0," HR probably just selected "single" on the new form without additional withholding, which doesn't withhold as much as the old "single 0" used to. You'll definitely want to update your W-4 for next year to avoid owing again. To cover a $5,300 gap, divide that by the number of pay periods remaining in the year. For example, if you're paid bi-weekly (26 pays per year) and have 20 pay periods left, you'd want about $265 extra withheld per check ($5,300 ÷ 20). The IRS Withholding Estimator at irs.gov can give you a more precise number based on your specific situation.

How accurate was taxr.ai compared to the regular IRS calculator? I've tried the IRS one before and it was so confusing I gave up halfway through. Does this actually explain things in normal human language?

I'm skeptical about these tax tools. How does it actually work? Do you have to upload all your personal financial info? Seems risky to share pay stubs with some random website.

The taxr.ai tool was much more user-friendly than the IRS calculator. It explained everything in plain English and gave me specific actions to take rather than just numbers. It pointed out exactly why I was underwithholding and showed the math behind it, which the IRS calculator doesn't do as clearly. For security, you don't have to upload full pay stubs - you just enter the relevant numbers from them. It's actually less information than you'd put into TurboTax or other tax software. It's more about analyzing the withholding patterns than having your complete financial picture. I was concerned about that too, but their privacy policy was pretty solid when I checked.

Wait, how does this actually work? Does it just call the IRS for you? I don't understand how this would get you through faster than calling yourself.

This sounds like complete BS. There's no way to "skip the line" with the IRS. They answer calls in the order received. I bet this is just taking your money for something you could do yourself for free.

It doesn't call for you - it uses a system that continuously redials the IRS using multiple lines until it gets through, then immediately connects you when it has an agent on the line. It's basically doing what you'd do if you had 20 phones and could keep redialing constantly until one got through. I was skeptical too! But the IRS phone system is completely overwhelmed most days. The average wait time when I called was 2+ hours, and often you just get a message saying they're too busy and to call back later. This service just handles the frustrating part of constantly redialing until you get in the queue. Once you're connected, you're talking directly with the IRS just like if you'd called yourself - no middleman or anything sketchy. You still need to verify your identity and everything else with the IRS agent.

@Nia Jackson LOL... yeah, maybe the agency should be called the IRBS! "

@Nia Jackson that s'not how it works. Claimyr is a software tool that calls ON YOUR BEHALF. It will call for you and stay on hold and forward the call to your phone.

@Matthew Anderson Nia was confused and wrong about what Zara was talking about. Claimyr is a software tool that calls the IRS ON YOUR BEHALF. It will call for you and stay on hold and forward the call to your phone. Yes it sucks the IRS can t'take the call, but Claimyr is legit.

That's a good point about the tax brackets. I did get a significant raise about 6 months ago that pushed me from around $155k to $178k. So maybe the withholding didn't properly adjust for that higher bracket rate?

Exactly. Withholding systems often don't immediately recalculate when you get a raise. They tend to keep withholding at the same percentage until you submit a new W-4. When you jump into a higher bracket like you did, the difference can be substantial. For example, if your withholding was calculated based on your previous $155k salary, it might be withholding at an effective rate of about 24%, but your new salary at $178k might require withholding at closer to 26-27% effective rate because more of your income is in that 32% bracket. This gap explains a good chunk of why you're owing more than expected.

This is really important! I had a similar situation where I was withholding correctly from my main job, but completely forgot about the $15k I made from a side gig. No withholding on that money meant I owed several thousand at tax time despite having "extra" withhheld from my primary paycheck.

You're absolutely right about the W-4 changes being the likely culprit here! The 2020 redesign completely eliminated the familiar "allowances" system that many of us relied on for decades. The concept of "single with 0 allowances" doesn't even exist anymore, which is why so many people are getting surprised. The new form tries to be more accurate by asking for specific dollar amounts instead of the old allowances, but it's created this weird transition period where conventional wisdom about withholding doesn't apply anymore. What worked reliably for years suddenly doesn't! For both you and the OP, it might be worth submitting a new W-4 with some additional withholding specified in Step 4(c). For someone at the OP's income level, they might need an extra $200-400 per paycheck withheld to avoid a surprise next year. The IRS has a tax withholding estimator on their website that's pretty helpful for figuring out the right amount. But yeah, I feel your pain - nothing like thinking you've got your taxes figured out only to have the rules change underneath you!