This model was designed as a result of a research made in different categories of services. The model defines quality service as disarrangement between the previous service expectations and the perception of the service offered; this can be measured from the difference of both concepts. With a higher difference between perceptions of the service and expectations, a higher quality result. The general disarrangement (Gap 5) can be the consequence of four disarrangements (Gap 1, Gap 2, Gap 3, and Gap 4). The SERVQUAL method has become of interest for a great number of investigators. (Ekinci et al., 1998). On those bases, quality concept is important for every organization and the people who integrate them. The eagerness of achieving perfection in the quality of the products and services offered by companies or organizations has impelled working with continuous improvement to achieve their goals, that is why service client is an important factor in organizations, but as the same time can be a problem for them because in the case that applications are not performed correctly could lead to the failure of an organization. In behalf of this, derives the demand of making the present investigation, with the intention of measure clients’ satisfaction level of the service offered in Agencia Fiscal del Estado de Sonora.