Double taxation is basically a sort of taxation in which a person/company's income tax is paid twice from the same income source. It occurs in mainly two different circumstances, which are;
1. Double taxation of shareholders and corporations: Shareholders are expected to receive a portion of the profits from any company or better yet corporation that they invested in. These corporations pay tax at the end of the year before they send out the profits to their shareholders, these shareholders are then expected to pay tax as well on the money they received from the corporation. When such a situation arises, double taxation occured.
2. International Double Taxation: International companies are the ones that face this problem. Provided they are functioning in more than one country(well that's the point of being international), they may be taxed on the income they earn in the foreign country and also taxed on that same income when it is sent back to their home country. When this scenario occurs, it means that the company has been double taxed.