Income tax is a newer form of tax that began to be applied after the Second World War II so it is considered to be a product of the 20th century. In the Republic of Croatia it has been applied since 1994 and from then on the tax rate has been followed by frequent legislative changes and harmonization processes. After the end of each financial year and the preparation of financial statements it is necessary to determine the income tax in accordance with the most recent changes to the legal regulations, taking into account the application of tax-deductible and non-deductible expenses, that is the reduction and the increase of the tax basis. The compilation and filing of the income tax return by the taxpayer and the calculation of the income tax per annum are regulated by the Act on Corporate Income Tax (NN: 177/04 - 115/16) and Corporate Income Tax Code (NN: 95/05 - 2/18). In the final thesis the company Zoe d.o.o. has been taken as an example in which the determination of the income tax liability and the accounting period of the company are shown. The aim of this paper is to demonstrate the determination of the income tax liability using the aforementioned example.