Also Step 2 phaseout for 2021:

The child tax credit won't begin to be reduced below $2000 per child until the taxpayers modified AGI exceeds:

$400,000 MFJ  and $200,000 for all other filing statues.

The second phaseout reduces the Child Tax credit by $50 for each $1000 by which the taxpayer's modified AGI exceeds the income amounts above.