What happens if you have multiple jobs (3) but just use the standard withholding for all of them?

You're right to be concerned. When you have multiple jobs but use standard withholding on each W-4, each employer calculates withholding as if their job is your only income. This almost always results in underwithholding. Here's why: Each job withholds taxes based on its own income level. So each employer is applying tax brackets and the standard deduction to just their portion of your income. But when you file taxes, all your income gets combined, pushing more of your total income into higher tax brackets. You should definitely adjust your withholding ASAP. The IRS has a Tax Withholding Estimator tool on their website that's designed specifically for multiple job situations. Input all your jobs and it will give you the correct withholding amount. Alternatively, you can use the Multiple Jobs Worksheet on the W-4 form. Another option is to request an additional dollar amount be withheld from one of your paychecks. This is often simpler than trying to adjust the withholding allowances on multiple W-4s.

I was in the same situation last year and discovered taxr.ai (https://taxr.ai) which seriously saved me. I had 3 jobs too and was completely confused about how to handle my withholding. I uploaded my paystubs from all three jobs and it analyzed exactly how much I was under-withholding and gave me specific instructions for fixing my W-4s at each job. The tool actually showed me I was going to owe about $3,200 at tax time if I didn't fix my withholding! It broke down exactly how much extra to withhold from each paycheck for the rest of the year to catch up. Super helpful when juggling multiple income sources.

Just wanted to give an update - I tried taxr.ai after asking about it and holy crap it was helpful! I was going to be short almost $2,800 in withholding for the year because of my combined W-2 jobs and weekend Uber driving. I didn't realize how much the self-employment taxes were adding to what I'd owe. The step-by-step instructions for fixing my W-4s were super clear. I filled out the new forms yesterday and already feel better knowing I won't get hit with a huge bill in April. Wish I'd known about this earlier in the year!

If you're already realizing you're going to be underwithheld, you might want to try reaching out to the IRS directly to discuss your options. But good luck getting through to them! I tried calling for weeks before discovering Claimyr (https://claimyr.com). You can see how it works here: https://youtu.be/_kiP6q8DX5c They got me connected to an IRS agent in about 15 minutes after I'd wasted hours on hold over multiple days. The agent was able to tell me exactly how to adjust my withholding for my situation and even explained how to avoid penalties for underwithholding. Was actually kind of shocked it worked so well after all the horror stories I'd heard about IRS phone wait times.

Coming back to eat my words about Claimyr. I tried it yesterday after being skeptical and I'm honestly shocked. Got connected to an IRS agent in about 20 minutes after trying unsuccessfully for literal days on my own. The agent confirmed I was going to be significantly underwithheld with my 3 jobs and helped me calculate exactly how much additional withholding to put on line 4(c) of my W-4 for each job. Turns out I was heading toward owing about $4,600 at tax time! Now I'm updating my withholding forms today and should break even by April.

Something nobody's mentioned yet - you might want to consider making estimated tax payments directly to the IRS rather than changing your W-4s, especially if we're already more than halfway through the year. That way you don't have to mess with your employer's payroll and can just send in the extra amount quarterly.

I had this exact issue last year! My solution was just adjusting the W-4 at my highest-paying job to withhold extra. I calculated roughly how much more I'd owe based on all three incomes, then divided that by remaining paychecks. For me it was about $175 extra per check from my main job. Much easier than trying to adjust all three jobs precisely.

This is a really common situation and you're smart to catch it now! With your combined income of $85,000 ($42k + $28k + $15k), you're definitely going to be underwithheld since each employer is treating their portion as if it's your only income. Here's what I'd recommend: Focus on your highest-paying job ($42k) for the adjustment. Use the IRS withholding calculator or add extra withholding on line 4(c) of that W-4. A rough estimate would be to withhold an additional $150-200 per paycheck from that job to cover the shortfall. The key issue is that your $15k weekend job is probably being withheld at around 12%, but when combined with your other income, those dollars are actually being taxed at 22%. That gap across all your jobs is what's creating the problem. Don't wait - the sooner you adjust, the less you'll need to withhold per paycheck to catch up by year-end. If you're already past mid-year, you might need to withhold even more per check or consider quarterly estimated payments as someone else mentioned.

One thing I'd add that hasn't been mentioned much - make sure you're also considering state taxes in your calculations! I made the mistake of only focusing on federal withholding when I had multiple jobs last year and got hit with a surprise state tax bill too. Each state employer was also treating their portion as my only income for state withholding purposes. In my case (California), the state tax brackets made this an even bigger issue than the federal shortfall. If you're using any of the tools mentioned here like the IRS calculator or taxr.ai, make sure they're accounting for your state taxes too. Some states have much steeper progressive tax rates than others, so the underwithholding problem can be amplified at the state level. Also, with your weekend gig bringing in $15k, double-check that your employer is actually withholding taxes from those paychecks. Some smaller employers or gig work might be treating you as a contractor (1099) rather than an employee (W-2), which would mean no withholding at all and you'd need to make estimated payments for that income.