You can still list your son as your dependant even if he is not transferring his disability tax credit to you. But please note that even if he uses the disability tax credit on his own return, he can still transfer any unused portions to you.
As long as the DTC form that was submitted to the CRA is still valid, you can continue to claim credits like the Caregiver credit. However, if you are claiming him as an eligible dependant, his income might now high enough that you can no longer claim the credit.
