President Trump’s administration is maneuvering to hand billions’ worth of tax breaks to the ultra-well-off without congressional approval. (Victor J. Blue/Bloomberg)

When I heard that the Trump administration was thinking of making up its own rules to reduce the tax that people pay on capital gains, I started laughing because I thought it was a joke.

Now, of course, we know that the administration is seriously considering going against 100 years of congressional precedent by ruling unilaterally that the cost of an asset that you sell should be adjusted for inflation between the time you bought it and sold it. So if you paid $10,000 for stock 10 years ago and sell it today for $20,000, your taxable gain would be only about $8,500 (by my estimate) rather than $10,000.

But you know what? The idea of indirectly lowering the capital gains tax is nuts. Not only for the reasons you’ve undoubtedly heard about — that about two-thirds of the tax is paid by the ultra-well-off among us and virtually all of it is paid by the top 10 percent — but because taxes on capital gains are already considerably lower than taxes on “earned income” such as salaries.

You don’t believe me? Look at these numbers:

The top federal tax rate on a long-term gain — profit on an asset held for more than a year before being sold — is 23.8 percent. The top rate for earned income is 38.45 percent. That makes the top cap gains rate 40 percent lower than the top rate on other income.

There’s another advantage that capital gains have, as well. To wit, you can generally take capital gains when it’s convenient, or defer them indefinitely.

There’s a final advantage, involving mortality.

If you want to help the next generation, you can hold on to assets worth considerably more than you paid for them and bequeath them to your heirs after you shuffle off this mortal coil.

For tax purposes, your heirs get to value these inherited assets at what they were worth the day you died. And neither your estate nor your inheritors owe any tax on the gain between when you bought the assets and when you died.

In any normal administration, I don’t think anyone would seriously consider indexing capital gains for inflation without running it by Congress.

But considering some of the games President Trump and his fellow travelers have played — invoking bogus “national security” concerns to impose tariffs by ukase and unilaterally deciding to hand $12 billion of taxpayer money to farmers and big farming corporations hurt by the tariffs — anything is possible.

In fact, the more uproar there is about this proposal to hand billions’ worth of tax breaks to the ultra-well-off without congressional approval, the more likely it is that Trump will order it done. That’s not based on any inside information — it’s based on watching Trump’s behavior.

Just so you know — I’d benefit personally if cap gains indexing goes into effect for this year. That’s because one of my long-term holdings (Time Warner) got taken over in June, creating a considerable taxable gain for me, and a publicly traded master limited partnership that I began buying into a decade ago is scheduled to be taken over by year-end.

But I’d much rather pay the tax that I owe under today’s rules than save money — possibly considerable money — by having Trump and his crew unilaterally change the rules about capital gains.

I’m already getting a big enough break by paying a much lower rate on my long-term gains than I pay on other income. As we used to say in Brooklyn, where I grew up: Enough, already.