My friend and former Trump first-term colleague, Stephen Miller, who is now the White House deputy chief of staff for policy in the second term, calls it the most essential piece of legislation in the Western world.

Of course, he’s referring to President Trump’s One Big Beautiful Bill, which is a once-in-a-lifetime opportunity to deliver on his core promises to lower taxes, secure the border, and rein in spending.

In Mr. Miller’s various X posts, he makes a bunch of key points, but I want to focus on some budget math that seems to be poorly understood by some of our conservative friends in the Senate.

First, even the Congressional Budget Office concedes that the House bill reduces mandatory spending by $1.7 trillion. These are the mandatory program savings from cutting waste, fraud, and abuse, and restoring appropriate eligibility requirements — especially for able-bodied males without dependents.

Then, they argue that extending the Trump tax cuts cost $3.7 trillion. And that leaves an increase in the deficit of about $2.5 trillion.

Wait a minute, though, extending the Trump tax cuts — and even adding about $300 billion in new tax cuts — can’t possibly increase the deficit.

Seven years ago, the CBO underscored Mr. Trump’s tax-cut related revenues by $2.3 trillion. In other words, actual revenues came in $2.3 trillion higher than the CBO estimates. So why won’t this happen again?

In fact, 100 percent bonus depreciation expensing for businesses is likely to produce an enormous growth dividend. New factories, machinery and equipment, and R&D will all make the economy growthier.

Working folks’ wages and business profits will be going up. And, at lower tax rates — perhaps the 15 percent Made in America corporate tax — tax revenues will climb rapidly.

The point is, as Mr. Miller makes clear, that the CBO’s estimate of a higher deficit from Trump policies rests on their false assumption that extending tax cuts and even adding some new tax cut wrinkles will increase the deficit.

It didn’t the last time. Why will it in the future? It won’t.

And Mr. Miller adds that when libertarians attack the deficit impact of the bill, they are attacking the tax cut.

Vetoing the bill would leave the GOP responsible for a $4 trillion tax hike. That would be political malpractice — of the worst kind.

So let me rework the numbers just a wee bit. 

Judging from the last seven years of higher tax revenues from the original Trump tax cuts, I’m going to extrapolate the $2.3 trillion CBO miss into a roughly $3 trillion revenue increase over 10 years.

And then I’m going to plug in $1.7 trillion in mandatory savings — which the CBO basically agrees with.

So that gives me $4.7 trillion in lower deficits over the next 10 years. Call it $5 trillion, just to use round numbers.

Now, that represents $5 trillion in deficit reduction — a far cry from the CBO estimate of a $2.5 trillion deficit increase.

Unfortunately, even that pro-growth deficit reduction plan of lower spending and lower taxes will not eliminate the deficit. As Senator Lankford of Oklahoma said on the show last night, “We’re not going to pay off the jumbo mortgage in one year.”

Yet lower spending, faster growth, and bigger growth dividends would in fact constitute — as Mr. Miller says — the best plan in the Western world.

From Mr. Kudlow’s broadcast on Fox Business Network.