The enhanced Child Tax Credit in the current bill goes into effect for the 2021 tax year (returns filed in 2022).
Congress Passes $3,000 Child Tax Credit for 2021 | Kiplinger
But in general, anytime Congress passes a tax law, the IRS must first develop procedures for implementation. Then TT must program, test and get them approved by the IRS. Until this happens, nothing can be released.
