This is not a programming issue. A taxpayer under age 18 can claim the credit if they're a full-year Colorado resident, have a Colorado tax liability, and are claiming a refund of Colorado wage withholding from a Form W-2.
As you indicate, the April 15th deadline applies if taxpayers were at least 18 years old and meet the other requirements.
However, no such age requirement exists for the October 15th deadline.
See 2023 TABOR Refund in the Colorado Department of Revenue's Taxpayer's Bill of Rights (TABOR) Information for more information.
