Yesterday I searched online and it seems the taxes on foreign income for Estonian residents are 20%
Well this is straight from horse's mouth.
"Residents pay tax on their worldwide income. Taxable income includes, in particular, income from employment (salaries, wages, bonuses and other remuneration); business income; interest, royalties, rental income; capital gains; pensions and scholarships (except scholarships financed from state budget or paid on the basis of law). Taxable income does not include dividends paid by Estonian or foreign companies when the underlying profits have already been taxed."
Last sentence means that if the Estonian holding received dividends from any subsidiary, those diviends will be tax exempt when distributed to Estonian residends.