The main purpose of this study is to estimate the fiscal size of early childhood education and care (ECEC) integration. To do this, this study estimated the current fiscal size of ECEC, and based on the estimation results, the fiscal cost of integrating ECEC was estimated in two ways: based on previous studies and based on standard unit cost of early childhood and standard unit cost of infant care. The study estimated the total size of ECEC financing as of 2022 was estimated to be KRW 19.34 trillion. Estimating the size of the fiscal size of ECEC integration based on previous studies, it was estimated that an average of about KRW 8 trillion would be required annually for five years starting in 2023. Based on standard unit costs, an annual estimate of KRW 741.8 billion could be generated over the five-year period from 2023. However, when considering the proposed increase based on the appropriate level of ECEC, it was found that a 10% increase would cost an average of KRW 1.92 trillion per year from 2023, and a 15% increase would cost KRW 5.75 trillion. Based on the findings of the study, implications for the establishment and financing of a special account for supporting ECEC are presented.