In developing countries, household expenditure on education is crucial in ensuring students' learning opportunities. In Cambodian secondary education, where informal fee charges and private tutoring in public schools are common, household expenditure is directly linked to student learning. This study adds a new perspective to previous research by examining the determinants of household expenditure on secondary education and private tutoring in Cambodia using a national representative sample. Utilizing Censored Least Absolute Deviation (CLAD), our paper reveals a notable gender disparity in educational spending, where households allocate more resources toward female students' education than male students. This gender gap extends to expenditures on private tutoring, potentially elucidating the observed reverse gender gap in recent high school graduation exam outcomes. The findings underscore the need to raise awareness among parents and caregivers about the importance of male education to address this expenditure gap. Additionally, the research highlights the influence of students' ethnic minority status on educational expenditure, revealing that households from ethnic minority backgrounds, typically with lower incomes, spend less on private tutoring. This discrepancy suggests a risk of widening academic achievement gaps between ethnic minority students and their majority counterparts. Further, the study observes a correlation between household income and educational spending, indicating that lower-income families are less likely to afford private tutoring, exacerbating educational disparities. The results call for policy interventions to address the gender and ethnic minority and income-related gaps in education, suggesting the necessity of support for disadvantaged families and a reevaluation of the private tutoring system to make education more equitable across Cambodia.