Both the amount and structure of tax revenue may change in time as they depend on numerous variables, including factors of the business cycle. However, the stability of tax revenue affects the balance of public finances and the ability to meet public obligations. The aim of this study is to evaluate the stability of tax revenue in Poland’s national budget in 2004-2020. The research results indicate that both the amount and the structure of tax revenue in the national budget in 2004-2020 were stable.