This study is devoted to the issue of the source of income from the sale of real estate for consideration under an annuity agreement. The article pays special attention to the issues related to the interpretation of the provision of Art. 10 sec. 1 point 8 lit. and the Personal Income Tax Act. In particular, the impact of the provisions of the above-mentioned of the Act on the interpretation and application of them in relation to a civil law contract, which is an annuity contract. The considerations focus on the question of whether the annuitant, in the event of selling real estate under a life annuity agreement, will pay 19% tax on the income calculated on the value of this real estate. Against the background of the above comments, it should be considered whether the actions taken by the legislator allowed for the creation of a properly functioning model of the source of income in the case of the disposal of real estate for consideration under an annuity agreement. The presented issues entail the inevitability of an analysis of legal issues in this field in terms of the nature of the changes, but also the related practical problems.