Taxes Solving Tax Issues How To Avoid or Resolve a Tax Audit Over Dependents Learn about the IRS rules for qualifying relatives and what to do if flagged By William Perez William Perez Twitter William Perez is a tax expert with 20+ years of experience advising on individual and small business tax. He has written hundreds of articles covering topics including filing taxes, solving tax issues, tax credits and deductions, tax planning, and taxable income. He previously worked for the IRS and holds an enrolled agent certification. learn about our editorial policies Updated on March 28, 2022 Reviewed by David Kindness Reviewed by David Kindness David Kindness is a Certified Public Accountant (CPA) and an expert in the fields of financial accounting, corporate and individual tax planning and preparation, and investing and retirement planning. David has helped thousands of clients improve their accounting and financial systems, create budgets, and minimize their taxes. learn about our financial review board In This Article View All In This Article Social Security Number Issues Rules for Qualifying Children Rules for Qualifying Relatives How the IRS Handles Audits What To Do If You're Flagged Defending Your Tax Return What to Do If You Lose Frequently Asked Questions (FAQs) Photo: gradyreese / Getty Images Blended families have become much more common, so it's not uncommon for two taxpayers to try to claim the same dependent in the same tax year. Complex family circumstances and a misunderstanding of the rules are often to blame. It can be unclear who should claim your child if you share custody with your ex. It might also be unclear who can claim your parents if you and your siblings help support them. IRS rules are complicated and multi-layered, but they make it clear who qualifies as a dependent and which taxpayers are eligible to claim them using a basis of financial support and time spent, among other criteria. Below, we'll discuss red flags, IRS rules for qualifying relatives and claiming dependents, and how to address or resolve issues in case of an IRS audit. Social Security Number Issues Claiming a dependent requires entering that individual's Social Security number (SSN) on your tax return. The IRS uses a computer system known as the Discriminant Inventory Function (DIF) to screen returns for duplicate Social Security numbers among other issues. The second tax return that's filed using an SSN or a dependent who's already been claimed by someone else will trigger a red flag from DIF. The second filer will receive an electronic-filing error message or a notice from the IRS via USPS mail. This is the first warning that something is amiss. Rules for Qualifying Children IRS rules for qualifying dependents are broken up into two categories: qualifying children and qualifying relatives. The IRS publishes tiebreaker rules to help taxpayers determine who gets to claim a dependent. The first rule states that a qualifying child dependent can only be claimed by the taxpayer with whom the child lived for more than half the tax year. Two or more taxpayers can't possibly meet this test. Other rules apply as well. The child: Must be related to you by blood, or be your adopted child or stepchild, or a foster child placed with you by an agency or court order. Descendants of these individuals qualify as well. Must be younger than age 19 on the last day of the tax year, or under age 24 if a full-time student. Exceptions to the age rule exist if the child is totally and permanently disabled. Must be younger than the taxpayer who's claiming the dependent, and the taxpayer's spouse, if married. Qualifying relatives can be older, however. Cannot file a joint return with a spouse unless it's only to claim a refund. Note A custodial parent can voluntarily give the dependent deduction to the other parent by providing a written release statement to the IRS on Form 8332. This sometimes happens in divorce situations. Rules for Qualifying Relatives A qualifying relative can't be your qualifying child, or anyone else's qualifying child, either, for that matter. A qualifying relative must have lived with you all year, although exceptions exist for parents or siblings. A gross income limit earned by the dependent applies as well. It's $4,300 for the 2021 tax year, the return filed in 2022. This limit is indexed for inflation, so it can increase a little each year. Finally, you must have financially provided for more than half your dependent's total support needs for the year. The IRS also allows taxpayers to waive or transfer the right to claim dependents to someone else. This situation might happen when two or more taxpayers jointly support their aging parent. They must together pay for more than half of that dependent's support, and the person claiming the dependent must personally contribute more than 10%. Note File IRS Form 2120, the Multiple Support Declaration, to allow one taxpayer to claim a dependent who's supported by more than one person. How the IRS Handles Dependent Audits The IRS will first attempt to determine which taxpayer isn't entitled to claim the dependent. It will send an audit notice to that individual. The IRS will randomly select one of the tax returns for an audit or send notices to both taxpayers if it can't determine on its own which taxpayer is eligible. It will automatically audit the other tax return that claimed the same dependent if the first taxpayer successfully defends their tax return. What To Do If You're Flagged First, go back to your tax return, and make sure you've correctly entered your dependent's SSN. You might have transposed numbers and inadvertently entered someone else's SSN instead. Reach out to anyone else who might have claimed your dependent if the number is correct—such as your ex. Find out whether they've claimed your dependent. Defending Your Tax Return Send your return back to the IRS for further processing if you're sure you meet all the criteria to qualify to claim your dependent. You might also want to hire a tax professional. Note Only attorneys, certified public accountants, and enrolled agents are authorized to represent you in an IRS audit. Be prepared to provide documentation that proves that you meet all the criteria to claim your dependent. You might have to prove your relationship to the individual, or that the dependent didn't provide more than half their own financial support. The more documentation you have, the better. Be ready to provide school or medical records to indicate that both you and your qualifying child dependent lived at the same address for more than half the year. You might have to submit additional documentation to qualify for specific tax breaks, such as proof of child care expenses, medical expenses, or higher education expenses. Some rules for qualifying dependents for deductions and credits can be marginally different. The IRS provides a list of acceptable supporting documents in IRS Form 886-H-DEP. Most dependent audit procedures will take place through the mail. The IRS will send you a request for information, and you can respond by sending in copies of your supporting documentation. What To Do If You Lose You can appeal the IRS auditor's decision, or you can take your case to the U.S. Tax Court if you and the IRS can't come to an agreement about your dependents, but an ounce of prevention is always worth a pound of cure. Do your best to avoid getting tangled up in this sort of situation in the first place. Address the issue of who gets to claim a dependent before everyone files their tax returns each year. Talking this over with family members can go a long way toward preventing problems. A Bigger Problem It's possible you might have a much bigger problem on your hands if you can't identify anyone else who claimed your dependent. Your dependent's Social Security number might have been compromised, and someone unknown to you may have used it to file a tax return. This fraud can trigger an IRS computer flag. Note The IRS has taken major steps against tax-related identity fraud, but the problem is by no means eradicated. Notify the IRS immediately if you have reason to believe that this has happened. You can find instructions on how to handle such a situation on the IRS website, including how to file a complaint with the Federal Trade Commission, notify the major credit bureaus, and complete and submit Form 14039, the Identity Theft Affidavit, to the IRS. Frequently Asked Questions (FAQs) How long can you claim a child as a dependent? As long as your child meets the other tests for qualifying as a dependent, you can claim them until they are 19 years old. This is extended to 24 years old if they are a full-time student. How do you claim a dependent on your taxes? To claim someone as a dependent, simply fill in their name, Social Security number, and relationship to you on Form 1040. If you have more dependents than will fit in the space provided, you can attach additional pages with more information. If someone else might be able to claim the same dependents, be sure to discuss this with them first to avoid a possible audit. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. IRS. "Whom May I Claim as a Dependent?" IRS. "Qualifying Child of More Than One Person." IRS. "Qualifying Child Rules." IRS. "Publication 929 Tax Rules for Children and Dependents." Page 24. IRS. "Publication 501 Dependents, Standard Deduction, and Filing Information." Page 20. IRS. "Dependents 2."