What did Donald Trump do today?

He observed the passage of a tax bill by repeating obviously false claims about its effect on his personal wealth.

Faced with a blizzard of questions about today's tax bill's obvious implications for Trump's wealth Press secretary Sarah Huckabee Sanders gamely repeated the official Trump line several times: "We expect that it likely will — certainly on the personal side — could cost the President a lot of money."

In reality, the bill will lower the rate paid by the wealthiest filers (like Trump), double the amount of money shielded from estate taxes (which Trump's estate will be subject to), massively lowers the tax on pass-through entities (which is what the Trump Organization is), and is chock full of breaks specifically aimed at the real estate industry (where Trump makes much of his money). All of these and any number of other provisions in the 560-page bill will lower, not raise, Trump's personal tax bill.

In fact, it is difficult to identify a single aspect of the bill that would in any way raise Trump's personal taxes--and Huckabee Sanders didn't try to. 

This isn't the first time Trump has told insultingly obvious lies about the way the tax bill will affect his personal fortunes, although Huckabee Sanders' version of them is performed with a straighter face than Trump himself usually manages. In a recent speech before a friendly crowd in Missouri, Trump struggled to deliver his lines without laughing, and he got a knowing chuckle from his audience when he claimed his "very wealthy friends" were "not so happy" about the plan. 

Unlike every president since Nixon, Trump continues to refuse to release any portion of his tax returns.

Why is this a bad thing?

• Good policy rarely needs to be lied about. 

• Past a certain point, lies can get so big and so obvious that their only real purpose is to show contempt for the people they're told to.