Will IRS penalize me for claiming both kids when ex-spouse and I should each claim 1 per year?

This is definitely a situation you need to address quickly. When divorced parents both try to claim the same child, the IRS has tiebreaker rules that apply regardless of what your divorce agreement states. However, your divorce agreement is a legal document, and violating it has its own consequences separate from IRS issues. Here's what happens: When your ex tries to file and claim your son, their electronic return will be rejected. If they file by paper instead, both returns will be processed initially, but the IRS will eventually notice the duplicate claim. They'll then apply their tiebreaker rules (usually favoring the custodial parent) and send notices to both of you. You have two options: First, you could file an amended return (Form 1040-X) immediately to correct your return before your ex files. This would mean repaying that portion of your refund. Second, you could wait and see if your ex notices, but this will likely lead to more complications.

I went through something similar last year and discovered taxr.ai (https://taxr.ai) which really helped me figure out my dependent situation. After my divorce, I wasn't sure who was supposed to claim which child since our agreement was vague. The site analyzed my divorce decree and tax situation and clearly laid out my options. What's helpful is they have tax professionals who understand both IRS rules AND how divorce agreements work together. They explained that IRS tiebreaker rules don't override your legal agreement - they're separate issues. Your divorce agreement is enforceable in family court even if the IRS initially allows your claim.

Just wanted to follow up - I decided to check out taxr.ai after seeing it mentioned here, and it was incredibly helpful! I uploaded my divorce decree and custody agreement, and within a day I got a detailed analysis of my dependent claiming rights. Turns out my ex and I were BOTH misinterpreting our agreement for years. They explained exactly how the IRS tiebreaker rules work in relation to our specific custody arrangement and highlighted the exact paragraph in our agreement that specified who claims which child. They also helped me prepare an amended return since I had made a similar mistake. Definitely worth it for the peace of mind alone!

After reading this thread, I think you should try Claimyr (https://claimyr.com) to talk directly with the IRS about this. I was in a similar situation last year and spent WEEKS trying to get through to the IRS on my own with no luck. Claimyr got me connected to an actual IRS agent in less than 20 minutes! You can see how it works here: https://youtu.be/_kiP6q8DX5c The IRS agent I spoke with explained exactly what would happen with competing dependent claims and walked me through my options. Much better than guessing or getting advice from friends. In my case, they confirmed I needed to file an amended return but also gave me info about setting up a payment plan since I couldn't pay it all back at once.

I need to eat my words from my previous comment. After getting nowhere with the IRS for over a week, I broke down and tried Claimyr out of desperation. I was STUNNED when they called me back in 35 minutes with an actual IRS agent on the line! The agent I spoke with was super helpful about my dependent issue with my ex. She explained exactly what documentation I needed to support my claim and the process for resolving the dispute. She even helped me set up a payment plan for the taxes I owed from a previous year, which I hadn't been able to do on my own. Seriously, this saved me so much stress and time - definitely not a scam like I initially thought!

I'm surprised nobody mentioned this yet - but your ex can still claim your son by filing a paper return instead of electronically. Then you'll BOTH get letters from the IRS asking for documentation to prove who has the right to claim him. The IRS will apply their tiebreaker rules: 1. They look at which parent the child lived with more nights during the year 2. If equal, then they give it to the parent with higher AGI 3. If neither of you are the parent, it goes to the person with the highest AGI So if your ex has documentation showing they were supposed to claim your son this year, you'll end up having to pay it back anyway plus potential penalties. Better to fix it now.

Something to consider - have you talked to your ex about this situation? I know you mentioned you don't communicate well, but maybe explain your financial hardship and offer to make it up next year by letting them claim both kids? Or perhaps work out some other arrangement to compensate them? I had a somewhat similar situation with my ex, and we managed to work out a deal where I claimed both kids one year when I really needed it, and then he got to claim both the following year. We put it in writing just to be safe. Sometimes being upfront is better than dealing with the fallout later.