Child Tax Credit Growth Act of 2006 - Amends the Internal Revenue Code to: (1) reduce from $10,000 to $5,000 the income threshold for determining the refundable portion of the child tax credit; (2) increase from 17 to 19 the age limit for a qualifying child under such credit; and (3) impose an additional income tax on individual taxpayers whose adjusted gross income exceeds $1 million.