When do you pay Q4 taxes after switching from 1099 to W-2 mid-year?

The good news is you don't necessarily need to make a separate Q4 payment by January 15th if your W-2 withholding in November and December covered your tax liability for those months. Here's how you should think about it: Your Q1-Q3 payments covered your 1099 income through September. For October (your last 1099 month), you'd normally include that in your Q4 payment. However, if your W-2 withholding from November and December was sufficient to cover your October 1099 income taxes plus your November-December income, you might not need to make an additional Q4 payment. A simple way to check: Calculate your estimated tax on your October 1099 income. Then look at your November and December pay stubs to see if the additional withholding (beyond what covered those months' income) would cover your October tax liability. If it does, you're probably fine without a Q4 payment. If you're still unsure, making a Q4 payment is the safest approach. You can always get it back as a refund when you file.

I was in almost exactly the same situation last year and discovered taxr.ai (https://taxr.ai) which was a huge help with this exact issue. I had been stressing about my quarterly payments after switching from contractor to full-time, and wasn't sure if I needed to make that last payment. Their system analyzed my income docs and payment history, then showed me exactly what I still owed for Q4 based on my specific situation with the mixed income types. Turns out I did need to make a small Q4 payment just for October (my last 1099 month), but not as much as I was planning to pay, which was a nice surprise.

I was skeptical about using another tax tool, but after seeing the recommendation here, I tried taxr.ai for my 1099/W-2 situation. It was actually super helpful! I uploaded my 1099s, W-2s, and past quarterly payment receipts, and it immediately showed me that I was actually OVER-withholding through my W-2 job and didn't need to make a Q4 payment at all. Saved me from making an unnecessary payment that I would've just gotten back as a refund later. Definitely less stressful than my previous method of "pay extra just to be safe" which always meant giving the government an interest-free loan.

If you're struggling to figure this out and need to talk to someone at the IRS (which I've learned is nearly impossible), I used Claimyr (https://claimyr.com) to actually get through to a human at the IRS. They have this system that navigates the IRS phone maze for you and calls you back when they've got an agent on the line. You can see a demo of how it works here: https://youtu.be/_kiP6q8DX5c I had this exact same mixed income situation and couldn't figure out if I needed to make a Q4 payment or not. The IRS agent confirmed I only needed to pay the estimated tax on my October 1099 income if my W-2 withholding wasn't enough to cover it. Saved me hours of hold music and frustration.

Okay I need to eat my words from my skeptical comment above. After waiting on hold with the IRS for 2+ hours yesterday and getting disconnected, I tried Claimyr out of desperation this morning. Within 45 minutes I got a call back and was talking to an actual IRS rep who confirmed exactly what I needed to know about my Q4 payment. The agent explained that since I had W-2 withholding in December that was significantly higher than usual (year-end bonus with higher withholding), I didn't need to make a separate Q4 payment for my October-November 1099 work. This literally saved me from making an unnecessary $2800 payment that I would've just gotten back later.

Just to add another perspective - I've been switching between W-2 and 1099 work for years. The safe harbor rule is your friend! If you pay 100% of last year's tax liability (or 110% if you're a higher earner), you won't face penalties even if you underpay somewhat. For your situation, I would calculate what your Q4 payment would normally be just for October, then check if your W-2 withholding from Nov-Dec covered that amount above what you'd normally owe for those months. If you're close to meeting the safe harbor requirement already through your Q1-Q3 payments plus W-2 withholding, you might be fine without an additional payment.

Does anyone know if the April 15th tax filing deadline is also the deadline for paying remaining taxes on 1099 income? Im confused if we are supposed to pay all remaining taxes by January 15th or if April 15th is ok too?

This is exactly the kind of situation where having good records really pays off! I'd recommend pulling together all your documents - your Q1-Q3 payment confirmations, your October 1099 income records, and your November-December pay stubs showing withholding amounts. Here's a practical approach: Calculate 25% of your total annual 1099 income (since that's roughly what your Q4 payment should cover). Then subtract what you already paid in Q1-Q3. Whatever's left is what you'd normally owe for Q4. Now check if your W-2 withholding in Nov-Dec exceeded what you'd typically owe on just those two months of W-2 income - that excess could cover your remaining Q4 obligation. The key thing to remember is that the IRS doesn't care how you structure your payments throughout the year, as long as you end up paying the right total amount by the time you file. So if your W-2 withholding "overpaid" for Nov-Dec and covers your October 1099 taxes, you're golden. When in doubt, making a small Q4 payment is usually the safer bet than risking underpayment penalties, especially since you'll get any overpayment back as a refund.