Last week, Carly Fiorina’s presidential campaign made an offer to reporters that was tantalizing to me, but probably to few other people on the planet: If we came in person to her campaign headquarters in Virginia, we could review her state income tax returns.

Ms. Fiorina had already put her and her husband’s federal income taxes for 2012 and 2013 online, along with a disclosure of financial assets that is much more detailed than required by law. (Ms. Fiorina, a former chief executive of Hewlett-Packard, and her husband have a net worth of precisely $58,954,494.88, according to her disclosure forms.) But I was mostly interested in the Fiorinas’ state income tax returns because they demonstrate a distinct — and distinctly annoying — feature of American taxes: the way states clamber over one another, trying to tax the same income, often generating a lot of paperwork but not much revenue.

Mr. and Ms. Fiorina had to file taxes in no fewer than 17 states in 2013, many of them with only the most tenuous connection to the Fiorinas or their financial interests. In 11 of those states, their tax bill was less than $250.

Of course, the Fiorinas make more money than most people, about $2.5 million in 2013, which is a major reason they were taxed in so many states. But the tax rules that cause the Fiorinas to have around a 1,000-page stack of state income tax returns also hit many Americans with more moderate incomes, requiring them to file multiple state income tax returns.