system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does Estonia have relatively low income inequality despite having a flat tax?
gpt
Estonia, and a lot of former Soviet countries have a lot of foreign direct investment, so the insanely rich people benefitting from their economy are in Germany and Sweden. 

Also as part of the conversion from Communism, many employees of those countries received shares or other forms of equity or profit sharing in the companies they worked for, helping distribute income.

Estonia also has a land and property tax system which offsets the flat tax on income, so you pay less on income taxes, but if you own rental properties or factories or other things like that, you'll be paying tax, while in some places like the US often large tax breaks are given to encourage that type of thing. 

The small size or Estonia also plays some part, with only 1.35 Million people 'The top 1% of the top 1%' is like 100 dudes, and those dudes are very likely to leave the country.