It isn’t. The point is that accruing back taxes requires payment and may, at the discretion of the IRS, mandate a criminal charge. He wasn’t charge at the time because he paid, but he could have been. So now they want him to have been.

However I think neither party really wants things to go this way, and Republicans are going to see lots of retaliatory investigation and charges brought over missed payments etc. should they pursue this.

A waste of time and money, doesn’t improve anything in the world, just creates more division. Basically the GOP motto.