I had a similar issue. I have three dependents that qualify for the CTC. I received advanced payments for one of them (totaling $1500). My full CTC should've been $9.000 minus the $1,500 I already received, leaving me with a CTC of $7,500. Turbo Tax only gave me a CTC of $5,000. I ran my information on Tax Slayer and Tax Act and both sites gave me the full $7,500 credit. Turbo Tax definitely has some flaws that need worked out.
