It's tax time in America — and not just for accountants.

The April 15 deadline for federal tax returns is fast approaching. At the same time, taxing the wealthy is becoming a big political issue in the leadup to the 2020 presidential election.

Rep. Alexandria Ocasio-Cortez, D-N.Y., proposed a 70 percent marginal tax rate on wealthy Americans as part of her co-sponsored Green New Deal in February. Since then, wealth inequality and taxes have become a common platform among Democratic presidential hopefuls.

That 70% sounds like a big number, but there's another country where some workers are paying similar taxes.

Sweden.

"The short version of the story is that Sweden and other Nordic countries ... have high taxes and they have fairly good economic performance," Torben Andersen, a professor in the Department of Economics and Business Economics at Aarhus University in Denmark, told CNBC. "And the simple explanation is that you cannot judge the effect of taxes without knowing what they are financing."

Sweden is known to have some of the highest taxes in the world. At the same time, unemployment is low and the country has posted better GDP numbers than the United States in recent years. Here's how a country with fewer than 10 million people pulled it off.

