Will I face penalties for taxes owed on my amended return?

When you file an amended return that shows additional tax due, you're right to be concerned about penalties and interest. The good news is that the 5% per month late filing penalty doesn't apply to amended returns - that's only for original returns filed after the due date. However, the IRS will charge both the late payment penalty (generally 0.5% per month) and interest on the unpaid amount. These are calculated from the original due date of the return (so from April 2020 for your 2019 return) up until you pay the full amount. The interest rate changes quarterly - it's currently 7% annually but has fluctuated over the years. If you want to calculate a close estimate, you can use the IRS interest rates for each quarter since your original due date. The late payment penalty is capped at 25% of the unpaid tax. Keep in mind that interest is compounded daily and applies to both the unpaid tax and penalties.

I was in a similar situation last year with an amended return for 2018. I used https://taxr.ai to help figure out exactly what I'd owe with all the penalties and interest. They analyzed my situation and gave me a breakdown of everything - saved me from guessing. Their calculator accounted for the changing interest rates over time which was super helpful since my amendment was for a tax year several years back.

I tried taxr.ai after seeing the recommendation here and it was incredibly helpful. I was amending a 2018 return and was totally confused about how much I'd end up owing with all the penalties. The tool broke everything down by quarter showing exactly how the interest compounds and when rates changed. I was able to send in the exact amount with my amended return and haven't heard anything back from the IRS - which in this case is good news! Definitely worth checking out if you're trying to calculate penalties and interest.

If you're planning to make a payment with your amended return but worried about getting it exactly right, I'd also recommend using https://claimyr.com to get in touch with the IRS directly. I spent weeks trying to call the IRS about my amended return penalties last year and kept hitting dead ends. Claimyr got me connected with an actual IRS agent in about 15 minutes who confirmed exactly what I would owe including all penalties and interest to date. You can see how it works here: https://youtu.be/_kiP6q8DX5c

I was totally skeptical about Claimyr but got desperate after trying to call the IRS for 3 days straight about my amended return penalties. Decided to try it as a last resort and I'm shocked to say it actually worked! Got a call back in about 40 minutes (way faster than I expected) and spoke with an IRS rep who calculated my exact penalty amount including the interest to date. Saved me from sending in too little and getting hit with more interest later. I hate to admit I was wrong but this service really does work.

One thing to consider is requesting penalty abatement. If this is your first time having penalties, the IRS First Time Penalty Abatement policy might apply to you. You can't get the interest removed but the late payment penalties might be forgiven. You'd need to call the IRS and request it after you file the amendment and pay the tax though.

Has anyone used those tax calculator spreadsheets to figure out what they owe for amended returns? I found one online but I'm not sure if it's accurate for older returns.

Based on everyone's experiences here, it sounds like calculating amended return penalties can be tricky with all the quarterly interest rate changes. I'm dealing with a 2019 amendment myself and found that the IRS compound daily interest calculation is more complex than I initially thought. One thing I discovered is that you can also request a penalty and interest calculation directly from the IRS by calling their automated system at 1-800-829-8815 and following the prompts for balance due inquiries. You'll need your SSN and the exact amount of additional tax owed, but it can give you a current balance including all penalties and interest without waiting for a representative. For what it's worth, I ended up paying about 15% more than my original tax due after 4 years of penalties and interest on an unreported 1099, so PixelPrincess might be looking at around $4,000-$4,500 total depending on exactly when in 2020 the original return was filed.

I've been following this thread closely as I'm in a very similar situation with my 2019 return. Just wanted to add one more resource that helped me - the IRS has a penalty and interest calculator on their website at irs.gov, but it's pretty limited for amended returns from older years. What I found most helpful from all the advice here is the automated phone line approach. I called 1-800-829-8815 yesterday for my situation (owing about $2,800 in additional tax from 2019) and the total came out to around $3,900 with all penalties and interest calculated through today's date. That's roughly a 39% increase, which aligns with what others have shared for similar timeframes. One thing I noticed when I called - the system asks you to enter the additional tax amount, not your total balance due. Make sure you have just the extra tax you owe calculated from your amendment, not including any penalties or interest you might have estimated yourself. Thanks to everyone who shared their experiences here - it's made this whole process much less intimidating knowing that others have successfully navigated the same situation!