In carrying on business, one of the first questions one needs to ask is 'what is the form of business organization to carry on such business?' Should it be a sole entrepreneur or should it be incorporated? Different form of business organization will be subject to different income (CIT) tax. This article will explore basic principles of corporate Income Tax in Thailand. in general the present system of corporate taxation in Thailand complies with internationally accepted standard the major tax base is the net profits of companies and juristic partnerships the calculation of net profits is subject to rules stipulated in section 65 bis and section 65 of the revenue code. the tax base is calculated on an accrual basis and there is no adjustment for inflation the standard tax rate is 20% on net profits the present Thai corporate income Tax system can be summarized as follows: