The SMEs (small and medium-sized enterprises) constitute 98% of the Moroccan economics. They represent the real nerve center of our economy with 40% of production and 31% of exports. They are present in all sectors of Moroccan economic activity; however, an alarming report from inforisk notes an 8% increase in business failure in 2018, compared with only 1% of corporate default growth worldwide. Indeed, 40% of the failures of the Moroccan companies are due to unpaid bills, and 70% of our companies support delays of payment higher than 90 days.In a context of recession and economic crisis, banks are increasingly reluctant to grant credit, not having or having very few assets, such as machines, premises and vehicles. The SMEs cannot access to conventional financing except at quasi-prohibitive rates, which makes late payments very difficult for the latter to absorb.The purpose of our study is to understand through system dynamics causal loop diagram, the impact of late payments on the financial health of the supply chain by considering two variables, namely the cash in hand and the inventory.