"Feeding data from U.S. tax returns into their model, Saez and Stantcheva find that the optimal capital income tax rate is definitely higher than zero."
Thank god !
"In fact, it appears that the optimal capital income tax rate is higher than the labor income tax rate"
That is ...
". If individuals are equally likely to change how much they work
or how much they save due to a change in taxes,
then capital income will always have a higher optimal rate than labor income"
"...capital income is much more unequally distributed"