Most Democrats would probably love to extend the expanded child tax credit permanently. At least a few Republicans would probably agree to that too. But by setting the expanded tax credit to expire four years from now, Democrats are able to ignore roughly $700 billion in future costs that have to be offset in order to use the reconciliation process.
“Democrats have no intention of taking away the child credit expansion after 2025—it is both popular and central to their poverty-reduction strategy,” says Brian Riedl, a senior fellow at the Manhattan Institute, a conservative think tank, and former Senate Republican staffer. “But sunsetting the policy after 2025 in this bill provides $700 billion in fake savings over the decade, as future Congresses will surely extend the policy.”
In other words, it’s a gimmick. A gimmick that, yes, Republicans have also used when trying to route major tax policy changes through the reconciliation system, but a gimmick nonetheless.