The aim of this article is to present the controversy of the allocation of revenues from sale of real estate to the proper source of revenues for the purposes of PIT – to income from paid disposal or to income from business activity. The correct classification of a benefit determines the tax base, revenue recognition timing, tax-deductible costs, principles for settlement of amounts due. The significance of this problem is even greater because the recognition of the sale of real estate as an activity within the taxpayer’s business activity affects not only the taxation rules, but also in many cases determines whether such taxation will occur at all. The assumption that the sale of real estate did not occur as part of business activity gives the opportunity to take advantage of the non-taxation preferences in the event of 5 years from the end of the calendar year of purchase or construction. The provisions, however, does not allow for the introduction of a clear and precise border between these two sources of revenues, which in consequence causes numerous disputes between taxpayers and tax authorities.