> Reading the article, it says that the figures are looking at actual income, not changes in asset prices.
They used actual income... but not for the 3.4% figure that's in the headline. When using actual income (i.e. personal income and cap gains) to calculate tax rate, they ProPublica article said:
> Collectively, the top 400 paid an average tax rate of 22% from 2013 to 2018.
So... where did they get the 3.4% figure that's in the headline? By including unrealized cap gains:
> Then they pay very little in tax when it’s measured against their growing wealth. The top 25 wealthiest Americans got $401 billion richer from 2014 to 2018, but paid just $13.6 billion in federal income taxes, a “true tax rate,” as we called it, of 3.4%.
What's a "true tax rate?", you ask?
> To capture the financial reality of the richest Americans, ProPublica undertook an analysis that has never been done before. We compared how much in taxes the 25 richest Americans paid each year to how much Forbes estimated their wealth grew in that same time period. We’re going to call this their true tax rate.
In other words, ProPublica invented the term 'true tax rate' to represent a fake tax rate that treats unrealized cap gains as income. The Guardian then wrote a headline that conflates the fake tax rate with the real tax rate.
Whenever you find yourself believing something that's not true, be sure to take a hard look at the source who mislead you. You'll find that it was rarely by mistake.