Behind all this market volatility, there’s another storm brewing

Because it's a tax RATE cut, there's more incentive to work. They predict minimal tax surplus losses. There's even a possibility that tax revenue increases. Either way, it's best to analyze economics at the base level.

Look at the the net exports equation. Net Exports = (Savings - Investment) + (Taxes - Government Expenditures). Even if there's a public sector deficit, the private sector can offset that deficit if the net savings is large enough. This means a tax cut could be strong enough to balance current account. While there may be some inflationary consequences, a tax cut is a great way to stimulate the economy without worrying too much about public debt.