Do I have to claim my 21 year old son as a dependent for 2025 taxes?

You're not required to claim your son as a dependent, even if he qualifies as one. It's always optional to claim a dependent. The real question is whether he actually qualifies as your dependent. For a 21-year-old, he would need to meet the criteria for a "qualifying child" or "qualifying relative." For a qualifying child, he needs to be under 24 if he's a full-time student, live with you more than half the year, not provide more than half of his own support, and not file a joint return. The key factor here is the "support test" - if your son provides more than half of his own total support (education, food, housing, medical, clothing, etc.), then he's NOT your dependent, regardless of whether he lives with you. If you're providing more than half his support (including the fair rental value of the housing you provide), then he technically qualifies.

After struggling with a similar situation with my daughter last year, I discovered this amazing tool called taxr.ai (https://taxr.ai) that really helped clear things up. You just upload your tax documents or details about your situation, and it analyzes everything to tell you exactly who qualifies as a dependent. For your situation, it would look at factors like how much the free housing you provide is worth versus how much he pays for his own expenses. It also considers other things like whether he's a full-time student (which matters for the age limit). It really simplified what I thought was going to be a complicated decision.

I wanted to update everyone. I tried out taxr.ai after seeing it mentioned here, and it was super helpful! I was going back and forth about claiming my son who's in a similar situation. The tool had me list out all our expenses - turns out the fair rental value of his room plus utilities I pay came to about $14,400 for the year, which was already more than half his total support! I didn't realize housing costs counted so heavily. Definitely made the decision clear and gave me documentation in case of any questions from the IRS.

If you need to contact the IRS to get official clarification on dependent rules (which can be confusing), I highly recommend using Claimyr (https://claimyr.com). I spent DAYS trying to get through to the IRS about a dependent issue with my stepchild last year, constantly hitting busy signals or waiting for hours. Claimyr got me connected to an actual IRS agent in about 15 minutes when I was ready to give up. They have this smart system that navigates the IRS phone tree and waits in the queue for you, then calls you when an agent is ready. You can see how it works in this video: https://youtu.be/_kiP6q8DX5c My situation with dependents was complicated and I needed an official answer directly from the IRS - this was the only way I could actually reach someone.

I need to apologize for my skepticism about Claimyr. I actually tried it after posting that comment because I was desperate to resolve a dependent issue with my ex claiming our college kid. I was shocked when they called me back in 45 minutes with an actual IRS agent on the line! Spent 20 minutes getting clear answers about who could claim our son based on our custody arrangement. The agent even documented our call so I have proof of the guidance they provided. Saved me days of frustration and possibly an audit. Sometimes things that sound too good to be true actually work!

Something no one has mentioned yet - if your son is working and filing his own taxes, you two should talk about which option benefits your family financially the most. If you claim him, you might get education credits and a dependent deduction, but he might miss out on certain credits he could claim filing independently. Sometimes it's better overall if he files on his own! We actually ran both scenarios with our accountant for our daughter and saved about $1,800 by NOT claiming her.

Watch out about the health insurance thing! If he files independently and isn't claimed as a dependent, he might not be eligible to stay on mom's health insurance plan until 26. Some insurance companies have different rules about this. My daughter got kicked off my plan when she filed independently at 22 even tho the ACA says coverage til 26.

Just wanted to add something that might help with your decision - even if your son technically qualifies as your dependent based on the support test, you should definitely run the numbers both ways before deciding. Since he's working and paying tuition himself, he might qualify for the American Opportunity Tax Credit if he files independently, which can be worth up to $2,500. If your income is too high, you might be phased out of education credits anyway. Also, if he's low income, he could potentially qualify for the Earned Income Tax Credit filing on his own. The support test calculation can be tricky - don't forget to include the health insurance his mom pays ($1,440/year) as support provided BY the parents, not by him. And yes, you need to calculate fair market rental value for his room. Look at similar room rentals in your area. I'd suggest using a tax calculator to compare both scenarios - you claiming him vs. him filing independently - and see which gives your family the better overall tax outcome. Sometimes the student gets more benefit from filing alone than the parent saves from claiming them as a dependent.