Indicating the child is disabled will have no affect on your tax return if the child is under the age of 13
IRS definition for being totally and permanently disabled -
Permanently and totally disabled.
Your child is permanently and totally disabled if both of the following apply.
• He or she can't engage in any substantial gainful activity because of a physical or mental condition.
• A doctor determines the condition has lasted or can be expected to last continuously for at least a year or can lead to death.
