The Senate Republican tax bill is built on shaky assumptions, such as sunsets of the individual tax provisions that the GOP argues will never actually happen. So the actual cost could be well above the official estimate of around $1.4 trillion — and credible analyses of the bill estimate that the additional revenue it creates through economic growth won't come close to offsetting that cost.
Note: "Likely cost" assumes the bill's sunsets and tax increases will not take effect; Reproduced from Center on Budget and Policy Priorities; Chart: Axios Visuals
Be smart: This bill costs a lot of money already, and members like Sen. Marco Rubio are still pushing for things like enhancement of the child tax credit. But sunsetting certain costly provisions to pay for the addition or enhancement of others doesn't actually prevent debt accumulation down the road if those sunsets never actually take place.