This paper describes a system dynamic model of credit burden, and it provides an estimation of credit volume. The elaborated model calculates and estimates household budget balance and budget forming flows: income and expenditures, loan and interest payments, increase in budget balance depending on the amount of the granted loan and the costs associated with the purchase of the loan object. The elaborated model can also be applied in analysis of the national economy and in entrepreneurship. The paper presents a method for determining the amount of the loan for purchasing a flat for a household. It also provides modeling results of Latvia's credit system and conclusions regarding its further development.