Using the microsimulation model ARAMMIS, this study attempts to measure the impacts of introducing an out-of-pocket (OOP) maximum threshold, or a safety net threshold, on consumer copayments for health care financed by the abolition of the Long-term Illness Regime (ALD) in France. The analysis is based on a comparison of different safety net threshold rules and their redistributive effects on patients’ OOP payments. We attach particular importance to indicators that bring to light changes in OOP payment levels and measure their impact on the equity of OOP distribution. The first section outlines the French National Health System to provide a better understanding of the stakes involved in reforming the health care reimbursement rules under the Compulsory Health Care Insurance scheme. In the second section, we describe the hypotheses retained, the database and the microsimulation model. The final section presents key findings, measuring the impact of the reform at both individual and system levels.