It has been reported that the higher the parents' education level and income, the better language performance after cochlear implant (CI). We investigate whether socioeconomic factors (household income, parental education level, type of family, and location of residence) affect the language performance after CI even when all financial support for examination, hospitalization, surgery, and language rehabilitation program after CI was provided by a third-party. Of the 892 pediatric patients who underwent CI between 2007 and 2020 at our institution, data from 109 patients who received full financial support were analyzed retrospectively. Categories of Auditory Performance (CAP) and K-Ling test (reading and speech) scores (preoperative and 3, 6 and 12 months postoperative) were analyzed according to socioeconomic factors. With third-party support, there was no significant difference in language performance based on the household income and location of residence. However, there were significant differences in K-ling-reading (phoneme) according to father's and mother's education level, K-ling-speech (phoneme, phonology) according to mother's education level and CAP score according to type of family (single-parent family or not). Additionally, when the mother's education level was less than a university degree, the mean age at the time of CI surgery was 3.1 years old, higher than 2.7 years old for mothers with a university degree or more (p <
0.001). Parental education level and family type significantly affected language performance following CI, even when financial support was fully provided. Additionally, children underwent CI earlier when the maternal education level was high.