Is there any benefit to opting out of the advance payments on the child tax credit (2021)?
As far as I can tell, worst case, is you end up with a bigger tax bill next year and maybe an underpayment penalty if your withholding or estimated taxes were so far off as to avoid safe harbor (100% of last year's tax due or 90% of this year's). So the net effect of opting out of advance payments is no different than increasing withholding.
Is there anything else I'm missing?