They aren't technically lying when they say most people will get a tax cut. In 2018, almost across the board, taxes paid will be down for everyone.

But this is a 10 year bill with provisions phasing in and out throughout, not just a one year tax cut. As we go further out in time, lower income's tax cuts get smaller and smaller, and eventually turn into an increase relative to the status quo.
Higher incomes tax cuts, however, become greater and greater as time goes on.

The republicans are betting (probably rightly) that people will be aware of the immediate impacts of the bill (more money in their pocket), but forget this tax bill even existed come 2022.

The phasing out of middle income cuts conveniently start phasing out after the 2018 and 2020 elections btw

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