Direct out-of-pocket payments for health care continue to be a major source of health financing in low- and middle-income countries. Some of these direct payments take the form of informal charges paid by patients to access the needed health care services. Remarkably, however, little is known about the extent to which these payments are exercised and their determinants in the context of Sub-Saharan Africa. This study attempts therefore to shed light on the role of supply-side factors in the occurrence of informal payments while accounting for the demand-side factors. The study relies on data taken from a nationally representative survey conducted among people living with HIV/AIDS in Cameroon. A multilevel mixed-effects logistic model is employed to identify the factors associated with the incidence of informal payments. Results reveal that circa 3.05% of the surveyed patients incurred informal payments for the consultations made on the day of the survey. The amount paid informally represents up to four times the official tariff. Factors related to: (i) human resources management of the health facilities (e.g., task shifting); (ii) health professionals’ perceptions vis-à-vis the remunerations of HIV-care provision and (iii) reception of patients (e.g., waiting time) significantly influence the probability of incurring informal payments. Also of note, the type of health care facilities is found to play a role: informal payments appear to be significantly lower in private non-profit facilities compared to those belonging to public sector. Our findings allude to some policy recommendations than can help reduce the incidence of informal payments.