In the USA companies are liable for corporate income tax , which also has a progressive element. No major country has adopted this form, although American tax authorities have shown an interest in it.
Shareholders receiving dividends do then end up paying income tax on profits already taxed.
Thirdly, there is the so-called imputation system in which some relief is offered to shareholders, to ensure that dividends are not subject to both income tax and corporation tax. This was the system introduced in the UK in April 1973, six years after corporation tax as such had itself been introduced. This piece of corporation tax was recognized as a payment of income tax on dividends by the shareholders who received them. It thus limited the degree to which profits distributed as dividends suffered both corporation tax and income tax. Now, however, ACT is set to be abolished.