Why can't I claim my children as dependents since I pay for all of their expenses all year?

[c-t-maloney]

my children are 13, 18 (mentally disabled and Court Appointed Guardians) and 20, full-time student

[SharonD007]

Your children will qualify as your dependents if they meet the following requirement:

For a Qualifying Child Dependent:

• They must be related to you. 
• They can’t be claimed as a dependent by someone else. 
• They must be a U.S. citizen, resident alien, national, or a Canadian or Mexican resident. 
• If they are married, they can’t file a joint return with his spouse. 
• They must be under the age of 19 (or 24 for full-time students). 
  • No age limit for permanently and totally disabled children. 
• They must have lived with you for more than half the year (exceptions apply). 
• They didn't provide more than half of their own support for the year. 

If your dependent doesn't meet the rules for a qualifying child dependent, they may meet the rules for a qualifying relative dependent:

For a Qualifying Relative Dependent:

• Their income must be less than $5,050
• You provided over half of their support
• They are not filing a joint tax return if married unless filing to claim a refund of withholding
• They must be a U.S, citizen, U.S. resident, U.S. national or resident of Canada and Mexico
• They must live with you all year, unless they falls under one of the categories—Does a dependent for 2024 have to live with me?

For additional information, review the TurboTax article Rules for Claiming a Dependent on Your Tax Return.