One of the most important functions of tax law is to ensure that the tax burden is distributed fairly within society. In this context, tax justice stands out as a principle that requires individuals to be taxed in accordance with their ability to pay. The principle of fairness in taxation is shaped by the concept of horizontal fairness, which means that people in similar economic circumstances are taxed at the same rate, and the concept of vertical fairness, which requires people with higher income levels to pay more tax. One of the seven income elements defined in the Income Tax Law (GVK), ‘other gains and income,’ is subject to various debates in practice because it covers income that is not continuous and is mostly exceptional in nature. This study aims to evaluate this income element in terms of the principle of fairness in taxation. To this end, the concept of taxable income is first explained, followed by a theoretical examination of other gains and income. Finally, the last section discusses deviations from the principle of fairness in current practices and develops proposed solutions.