President Trump signs the Tax Cut and Reform Bill on Dec. 22, 2017. (Jabin Botsford/The Washington Post)

By far the most significant piece of legislation to have been signed into law by President Trump was December 2017′s bill slashing corporate tax rates and reducing some income taxes for a decade. It has not only been the high-water mark of Trump’s presidency, as far as legislation goes, but also was a significant victory for his party broadly, which had been agitating for such a move for years.

While the aftermath of those cuts has been mixed — some higher wages and a spiking deficit — the cuts and Trump’s presidency broadly appear to have had one marked success: increasing Republican confidence in the fairness of the tax system.

The Pew Research Center continued several years of polling looking at how Americans view the tax system with new data released Thursday. The most significant finding was that, on a number of metrics, the gap between Democrats and Republicans has grown much, much wider.

Consider, for example, a battery of questions about the fairness of what various groups pay. From 2015 to 2017, the percentage of Republicans saying that some corporations or some wealthy people didn’t pay their fair share in taxes dropped 11 and nine percentage points, respectively. By this year, those percentages had dropped 13 and 12 points. Among Democrats, views that the wealthy and corporations didn’t pay their fair share climbed by 6 and 8 points, respectively.

(Philip Bump/The Washington Post)

Perhaps more interesting, the percentages of Republicans saying that the amount they paid was unfair also dropped after the passage of the Republican tax bill — while the percentage of Democrats saying that they paid an unfair amount had climbed. We noted last year that whether people believed they had received a tax break in their paychecks depended on their partisan identity. Republicans are now also much less likely to say the tax system is complex — long a Republican complaint about federal taxes.

Before Trump took office, Republicans, like Democrats, were more likely to say that the tax system unfairly favored the powerful than that it was generally fair to most Americans. Since Trump took office, that has flipped. More Republicans now say the system is fair than unfair — while the gap between the two positions among Democrats has widened.

(Philip Bump/The Washington Post)

There’s another factor that plays a role here, as Pew’s data indicates: income.

Since 2017, the gap between Democrats and Republicans on the question of the fairness of the tax system has widened dramatically. Then, there was a two-point difference between the parties. Now, there’s a 32-point gap. Why? Well, poorer Republicans are more likely than poorer Democrats to say that the system is fair, by a 16-point margin. But among wealthier members of each party, the gap is a staggering 47 points.

(Philip Bump/The Washington Post)

The gulf is a result of movement by both parties. Wealthier Republicans are much more likely to see the system as fair than poorer Republicans. But wealthier Democrats are much less likely to see the system as fair than are poorer Democrats.

It’s certainly the case, as with that survey that found Republicans more likely to say they had gotten a tax cut, that support for Trump plays a role. He says the tax cuts made the system better, and so Republicans will accept — and Democrats reject — that premise.

But there’s another component, highlighted by that last question, in particular. Wealthier Americans saw much bigger benefits from the Republican tax bill, something that wealthy Republicans seem to consider fair and that wealthy Democrats consider unfair — considerations that overlap with partisan positions. In other words, there were real political reasons to see shifts in how the tax system operates, independent of Trump. The tax system did change, and in a way that Republicans wanted to see and Democrats didn’t.

And so: more division.