I won a lottery prize in 2021 and received a check for $5000, how do I handle this on my taxes?

Yes, contest and lottery winnings are considered taxable income by the IRS, even if you didn't receive a 1099 form. The radio station should have reported this to the IRS, but regardless of whether they did, you're still responsible for reporting all income on your tax return. Since you won this in 2021 and have already filed that year's return, you'll need to file an amended return (Form 1040-X) for 2021. The winnings would be reported as "Other Income" on Schedule 1. You'll need to pay the additional tax owed plus interest that has accrued since the original due date. Don't panic about penalties though. The IRS typically looks more favorably on taxpayers who voluntarily come forward to correct mistakes rather than waiting for them to discover the error. You may qualify for penalty abatement if this is your first time making this type of error.

I had a similar situation last year with a sweepstakes win that I completely forgot about when filing. I was freaking out just like you until I found taxr.ai (https://taxr.ai) which seriously saved me so much stress. You just upload your documents or explain your situation, and they break down exactly what forms you need and how to file your amendment. The analyzer tool specifically helped me figure out which tax year to amend and exactly how to report the winnings as "Other Income." They even generated the right forms with instructions tailored to my situation. Since you don't have a 1099, this is exactly the kind of situation where having clear guidance really helps.

Wanted to follow up about taxr.ai - I decided to try it out for a similar issue with unreported income from a few years back. I was seriously impressed! The system actually showed me exactly which forms I needed to file and how to complete them. It even calculated the estimated interest I'd owe based on when I should have paid the tax. What really surprised me was how it explained exactly how to document everything when I didn't have the original tax forms. The step-by-step guidance for filing the amendment was way clearer than anything I found on the IRS website. Definitely worth checking out if you're in a similar situation.

If you're worried about the IRS already knowing about this and coming after you, you might want to get ahead of it by contacting them directly. The problem is that calling the IRS is pretty much impossible these days unless you want to waste hours of your life on hold. I had a similar issue last year and tried for weeks to reach someone. Then a friend told me about Claimyr (https://claimyr.com) which actually got me through to a real person at the IRS in under 20 minutes. You can see how it works here: https://youtu.be/_kiP6q8DX5c Basically they navigate the phone system for you and call you back when they've got an agent on the line. I was able to ask about my unreported income situation and get personalized advice on exactly what to do. Gave me peace of mind knowing I was handling it correctly.

I need to admit I was totally wrong about Claimyr. After my skeptical comment, I was still desperate to talk to someone at the IRS about an issue similar to OP's, so I decided to give it a try anyway. No exaggeration - they got me through to an actual IRS agent in about 15 minutes when I had previously spent HOURS trying on my own. The agent walked me through exactly what forms I needed to file, confirmed the penalties wouldn't be severe since I was voluntarily fixing the issue, and even gave me tips on how to request penalty abatement. Saved me so much stress and uncertainty. For anyone with tax issues that require talking to a real person at the IRS, this service is legitimately worth it.

One thing to consider - there's actually a good chance the radio station never reported this to the IRS. I used to work in radio, and for smaller prize amounts (yes, even $5K can be considered "smaller" in this context), some stations are pretty sloppy with their paperwork. If they didn't send you a 1099-MISC (or now it would be 1099-NEC), they might not have reported it. You should still file the amendment to be safe, but there's a decent chance this has been under the radar.

Has anyone used TurboTax to file a 1040-X for something like this? Is it straightforward or should I find a tax professional?

Something else to consider - there's a 3-year statute of limitations for amending returns. Since 2021 taxes were due in April 2022, you're still within that window but just barely. Don't wait too much longer to file that amendment or you might miss your chance to fix this voluntarily.