In the contemporary literature, several studies have attempted to see the effect of gender inequality and public expenditure on inclusive education. However, few have attempted to determine the gender inequality threshold. In this study, we first examined the threshold of gender inequality which, when exceeded, the effect on inclusive education becomes negative. Second, we examined the effect of public expenditure on inclusive education in 17 countries in sub-Saharan Africa, in the period from 2000 to 2019. The fixed-effect panel data model was used. The following results have been established: (i) the gender inequality threshold from which the effect of gender inequality becomes negative on the gross enrolment rate is respectively established at 0.38 in primary and 0.37 in secondary. At the higher level, the effect of gender inequality is linear and negative on the gross enrolment rate; (ii) public expenditure on education has a positive and significant effect at the primary and secondary level on inclusive education. However, its effect at the higher level is negative. As implications, the results constitute and intermediate objective for the countries for the sub-Saharan Africa which failing to achieve gender equality, would benefit from reducing inequality to 0.38 at primary level and 0.37 at secondary level. Secondary, education in order to cancel out the negative effect of gender inequality on gross enrolment rates at the primary and secondary level. Secondly, states must further consider public education expenditure as a relevant instrument for achieving SDG 4.