As the advance Child Tax Credit payments began arriving a few weeks ago, many parents were surprised to receive a different amount than expected, and many have had questions about the amounts they received. Parents with children who will turn 6 or 18 by the end of the year may be receiving less than expected: only children under the age of 6 are eligible for $300 payments, and only children between the ages of 6 and 17 are eligible for the maximum $250 per month payment.