The article investigates the influence of the growing public expenditures on health caused by the demographic aging of the population, on the stability of public finances in the context of the establishment of the "longevity economy". The author conducts a scenario based assessment of the sustainability of public finances in Ukraine in the medium and long term, based on the calculation of the fiscal gap indicator.
In particular, investigated the "stress effect" of the changes in the indicators of macroeconomic development and the fiscal position on the sustainability of public finances under the condition of realization of the historical scenario. The author proves a significant influence of demographic aging of Ukraine's population on the sustainability of public finance. It is determined that in the long term there will be a fundamental transformation of the "spending profile" in the health care by sex-age groups, which, for example, is due to a shift in consumption of these expenditures by the population of older age groups and their increased share.
The author substantiates the necessity to expand the fiscal space for fulfilling the normative requirements of the Ukrainian legislation on health financing based on the calculation of the necessary structural primary balance to overcome the fiscal gap, which is proposed to be used as one of the benchmarks for the implementation of fiscal policy in order to attain medium and long-term sustainability of public finances for a given period of .fiscal adjustment. It is proposed: to monitor and control the pace and the growth factors of health care expenditures in the medium and long-term; to develop indicators for assessing the fiscal space for healthcare with due regard to potential change in the demographic structure of the population; to assess the transformation of the fiscal space to finance the health care in the context of the establishment of the longevity economy while respecting the sustainability of the system of public finances.

Keywords: fiscal sustainability, public finances, health care, fiscal gap, demographic aging, fiscal space, age-related costs

The article deals with the impact of the COVID-19 pandemic on the financing of the health care system, and the main challenges to the stability of the financial mechanisms of post-pandemic health care development have been identified. The author substantiates the peculiarities of the crisis of health care financing in the conditions of the current pandemic, further economic recession and decreased fiscal sustainability. The global practice of fiscal response to the manifestations of the COVID-19 pandemic has been systematized and the volumes of the corresponding financing in the countries with insurance and budgetary systems of health care financing have been estimated.
The article identifies mechanisms for the transformation and expansion of the fiscal space in the context of expanded financing of the growing need for medical care in the face of new epidemic risks in different countries. Most often, the expansion of a country's fiscal space is carried out by: redistributing the existing amount of government expenditure for health care and redirecting funding flows from financing certain types of medical care to financing programs to overcome and combat COVID-19; changes in the priority of government health expenditure to combat COVID-19 compared to other budget expenditures on the social sphere and economic development; and using national reserve funds and emergency funds.
It has been found that in the field of health care, the vast majority of countries have reduced the economic and territorial deprivation of all population groups in access to the diagnosis and treatment of COVID-19. The author emphasizes the weaknesses of insurance based and decentralized health financing mechanisms to respond to the growing need for health care and financial stability during the pandemic. Substantiated the necessity to expand the fiscal space needed to cover the fiscal gap in Ukraine caused by the requirement to increase health care financing in response to new epidemic risks amid growing budget deficits, public debt and economic downturn.

Keywords:COVID-19, pandemic, fiscal sustainability, public finances, health care, fiscal space, health financing crisis, public health expenditures, fiscal gap, measures to combat COVID-19