W-4 Step 4c Question - How to Add Extra Withholding for 2025 Taxes?
So I just got hit with a tax bill this year because my employer hasn't been taking out enough for income tax. Not cool! I want to fix this NOW so I don't end up owing a bunch again next year. I'm updating my W-4 form and I filled out Steps 1-3 without any problems. But I'm confused about Step 4c (Extra withholding). If I put an amount in there, is that how much EXTRA they'll take out of each paycheck? Or should I just leave it blank and trust my employer to figure out the right amount? I really don't want another surprise tax bill next year. Any advice on how to handle this Step 4c part would be super helpful! Thanks!
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Hannah White
Step 4c is specifically for any additional withholding you want taken out of each paycheck beyond what the W-4 calculations determine. Your employer won't automatically figure this out for you - you need to decide what amount to put there, if any. If you leave Step 4c blank, your withholding will be based only on the information you provided in Steps 1-3. Since you mentioned you're already owing taxes with this approach, you probably should put something in 4c. A simple approach is to take the amount you owed this year, divide by the number of paychecks you get annually, and put that as your additional withholding. For example, if you owed $1,200 and get paid twice monthly (24 paychecks), you could put $50 in Step 4c.
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Michael Green
•Does adding an amount in 4c mean that's taken out of EVERY paycheck? Or is it a one-time thing? And is there a way to figure out exactly how much I should put without just guessing based on last year?
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Hannah White
•Yes, the amount you put in Step 4c will be withheld from every paycheck. It's not a one-time deduction, but an additional amount taken from each pay period. For a more precise calculation rather than just using last year's numbers, you could use the IRS Tax Withholding Estimator tool on the IRS website. It helps you determine if you're having the right amount withheld based on your specific situation. You'll need your most recent pay stubs and tax return to use it effectively. The tool will tell you if you need additional withholding and can suggest an amount for Step 4c.
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Mateo Silva
After struggling with the exact same issue last year, I finally found a solution with taxr.ai (https://taxr.ai). I uploaded my last pay stub and tax return, and it analyzed exactly why I was underwithholding. Turns out I had multiple jobs but wasn't accounting for them properly on my W-4. The tool suggested a specific amount for Step 4c based on my actual income pattern instead of just guessing. It even showed me how much I'd owe at different withholding amounts so I could decide exactly how much extra to have taken out each paycheck.
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Victoria Jones
•How accurate was it compared to the IRS withholding calculator? I tried using that but it was super confusing with all the questions.
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Cameron Black
•Does it work if you have 1099 income too? I have a side gig that doesn't withhold taxes at all and always screws up my calculations.
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Mateo Silva
•It was way more accurate than the IRS calculator for me. The IRS tool seemed to underestimate my tax liability, while taxr.ai nailed it almost exactly. Plus it's much easier to use - I just uploaded documents instead of manually entering dozens of fields. The tool definitely handles 1099 income. You can add multiple income sources including W-2 jobs, self-employment, and even investment income. It'll calculate your total tax liability and then suggest exactly how much extra withholding you need on your W-4 to cover everything.
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Victoria Jones
Just wanted to follow up - I tried taxr.ai after posting here and WOW what a difference! I've been underwithholding for years and the IRS calculator never got it right. The taxr.ai analysis showed I needed to put $178 in Step 4c of my W-4 which is WAY more than I would have guessed. They showed exactly how they calculated it based on my tax bracket and other income. Totally worth it to avoid another tax bill next year. Already submitted my new W-4 to HR yesterday!
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Jessica Nguyen
I had this exact problem last year and tried everything to fix my withholding. After months of not getting anywhere with my company's payroll dept, I finally used Claimyr (https://claimyr.com) to speak directly with an IRS agent about my withholding issues. There's a demo of how it works here: https://youtu.be/_kiP6q8DX5c The agent walked me through exactly how to calculate the right amount for Step 4c based on my specific situation. Turned out my employer had me classified wrong in their system which was affecting my withholding calculations!
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Isaiah Thompson
•How long did you wait to talk to someone? Every time I call the IRS I'm on hold forever and then get disconnected.
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Ruby Garcia
•This sounds like BS tbh. Nobody gets through to the IRS these days. You're telling me this service somehow magically gets you past the hold times? How much does it cost?
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Jessica Nguyen
•I got through to an agent in about 20 minutes. Before using Claimyr, I spent literally 3 hours on hold and then got disconnected right as someone picked up - I almost threw my phone across the room! It's definitely not BS. They use some technology that keeps your place in the IRS phone queue so you don't have to stay on hold yourself. When an agent is about to pick up, they call you and connect you. It was absolutely worth it to get my withholding straightened out properly.
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Ruby Garcia
Ok I have to eat my words here. After posting that skeptical comment, I actually tried Claimyr since I needed to talk to the IRS about my withholding issues too. I was SHOCKED when they called me back after only 35 minutes (I was quoted a 2.5 hour wait time on the IRS line). The IRS agent I spoke with explained that I had been filling out my W-4 all wrong for years. For my situation, she recommended putting exactly $125 in Step 4c per paycheck. Already seeing the difference in my latest paycheck and it's such a relief knowing I won't owe thousands next April.
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Alexander Evans
Another option is to use the Multiple Jobs Worksheet that comes with the W-4 instructions. If you have more than one job or your spouse works, this is super important. That was my problem - I have a side job teaching yoga on weekends and wasn't accounting for that income.
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Evelyn Martinez
•Is that worksheet the same as checking the box in Step 2c? My husband and I both work and I always get confused about whether to check that box or do something with Step 4.
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Alexander Evans
•The worksheet is more precise than just checking the box in Step 2c. Checking the box is a simplified method that basically tells your employer to withhold at a higher single rate, which works okay if both jobs have similar pay. The worksheet gives you a specific dollar amount to put in Step 4c based on your actual situation. It's especially useful if your jobs have different pay levels or if you have more complicated situations. For example, in my case, my main job pays about $65,000 and my yoga teaching brings in around $15,000, so the worksheet gave me a much more accurate number than just checking the box would have.
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Benjamin Carter
Has anyone tried just putting their total tax bill from last year divided by their number of paychecks as their 4c amount? That seems like the easiest method and then you'd at least cover what you owed before?
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Maya Lewis
•I did this last year and it worked pretty well, but I didn't account for a raise I got midyear so I still ended up owing a little bit. If your income is going to change, you should probably add a buffer.
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Isaac Wright
Probably gonna sound dumb but how do I actually change my W-4 after I've figured out the right number for 4c? Do I just email HR or is there some official form I need to fill out?
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Hannah White
•Not a dumb question at all! You need to complete a new W-4 form and submit it to your employer's HR or payroll department. Most companies have an electronic system where you can update your W-4 online through your employee portal. If not, you can download the form from the IRS website, fill it out, and give the physical form to your HR department. Your employer is required to implement the new withholding by the start of the first payroll period ending 30 days after you submit the form. So it might take a pay cycle or two before you see the change in your withholding.
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A Man D Mortal
I was in the exact same boat last year - ended up owing $2,800 because my withholding was way off! Here's what I learned after going through this painful process: Step 4c is definitely the way to go for extra withholding, and yes, whatever amount you put there gets taken out of EVERY paycheck. Don't leave it blank if you're already underwithholding. My approach was to be a bit conservative and overestimate rather than underestimate. I took what I owed last year, divided by my number of paychecks, then added an extra $20-30 per paycheck as a buffer. Better to get a refund than owe again! One thing to keep in mind - if you get any raises or bonuses during the year, or if your situation changes (marriage, kids, etc.), you might need to adjust your W-4 again. I actually updated mine twice last year as my income changed. The peace of mind is totally worth it. Getting that first paycheck with the higher withholding was such a relief knowing I wouldn't get hit with another surprise tax bill.
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Omar Hassan
•Thanks for sharing your experience! That $2,800 surprise sounds awful. I'm definitely leaning toward being conservative like you did - I'd rather get a small refund than owe money again. Quick question: when you say you added an extra $20-30 buffer per paycheck, did you find that was enough to cover any income changes during the year? I'm expecting a possible promotion mid-year and want to make sure I don't end up short again even with the raise.
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