The final Republican tax bill would expand budget deficits by more than $1.4 trillion over a decade, according to a "very preliminary" analysis by the congressional scorekeeper Joint Committee on Taxation.
It would mean the GOP plan slips under the maximum $1.5 trillion it is allowed to add to the deficit under rules set by the Senate earlier this year.
It will not quash criticism from some Democrats, who have called Republicans hypocritical for sounding alarms about deficits in recent years and then voting for the tax proposal. A separate JCT assessment of an earlier version of the bill said it would tack more than $1 trillion on to budget deficits even after economic growth is taken into account.
House Speaker Paul Ryan and other Republicans have signaled that they want to turn to reforms of social safety net programs to help to make up for budget deficits next year.