Isaac and Cynthia are married filing jointly taxpayers. Their modified adjusted gross income (MAGI) for 2020 is $53,000. They have three children and qualify for the full Child Tax Credit for each, which means they get a $6,000 credit (3 x $2,000 = $6,000). They complete their Form 1040 and determine their Federal income tax bill is just $1,000, leaving them with $5,000 in unused credit. Isaac and Cynthia qualify to claim the Additional Child Tax Credit and can generally receive a maximum income tax refund for what amount?