Ovim radom se prikazuje postupak utvrđivanja osnovice poreza na dobit trgovačkog društva u poreznom sustavu Republike Hrvatske. Zakonska osnova oporezivanja porezom na dobit pronalazi se u Zakonu o porezu na dobit i Pravilniku o porezu na dobit, te ostalim zakonskim propisima koji uređuju poslovanje trgovačkih društava u Republici Hrvatskoj. Porezni obveznici oporezivanja porezom na dobit su najvećim dijelom trgovačka društva, ali i inozemni poduzetnici, neprofitne organizacije i fizičke osobe ukoliko ispunjavaju uvijete propisane Zakonom. Ovaj rad, u svojoj suštini, prikazuje sve moguće Zakonom propisane kategorije povećanja i smanjenja osnovice poreza na dobit, te njen izračun na primjeru trgovačkog društva sa sjedištem u Republici Hrvatskoj. Rad je koncipiran u nekoliko cjelina. U uvodu je ukratko opisan razvoj porezne kategorije poreza na dobit kroz povijest. U drugoj cjelini nalazi se pregled zakonske osnove oporezivanja. Treća cjelina prikazuje kategorije povećanja porezne osnovice. Četvrta i peta cjelina prikazuju kategorije smanjenja porezne osnovice te porezne olakšice i oslobođenja. Šesta cjelina prikazuje postupak utvrđivanja porezne osnovice, a sedma cjelina praktični primjer izračuna. Na kraju je dan osvrt na diplomski rad u cjelini.

This paper shows a method of determining the profit tax base of a company in the tax system of the Republic of Croatia. The legal basis of taxation on profits is found in the Law on Corporate Income Tax and Regulations on Corporate Income Tax and other legislation governing the operation of companies in the Republic of Croatia. Taxpayers of taxation on profits are mostly companies, but also foreign entrepreneurs, non-profit organizations and individuals if they fulfill the conditions prescribed by the Law. This work, in its essence, shows all possible statutory categories of increase and decrease of the tax base, and its calculation on the example of a company based in the Republic of Croatia. The work is divided into several sections. In the introduction, the paper describes the development of tax categories of income tax througout history. In the second part of the review is the legal basis of taxation. The third section shows the categories of increasing the tax base. The fourth and fifth section shows categories reducing the tax base and tax deductions and exemptions. The sixth section shows the process of determining the tax base, and the seventh practical example of calculating tax base. Finally, comments on the thesis in full.