The article presents the results of the analysis of the impact of changes in the pension legislation adopted in October 2018 on the main parameters of the mandatory pension insurance system. It is shown that without raising the retirement age and maintaining the current structure of the insurance pension system until 2050, it would be possible to ensure the annual indexation of pensions in terms of inflation even with minimal economic growth. However, to maintain the ratio of the average pension to the average wage at the current level, raising the retirement age is only one of the necessary measures to stabilize the situation in the period up to 2028. The paper presents the impact of reducing informal employment, increasing the requirements for the length of insurance tenure and increasing the minimum number of individual pension points on the replacement rate. The estimates of tax rates and budget transfer amounts at which it is possible to ensure the replacement rate at the current level (33%) or increase it to 40% are given in for the period up to 2050.