Background and Objectives: Annually, a large amount of fees that are paid by hospitals, will not be reimbursed as deductions by health insurance which imposes irreparable financial losses on hospitals. The purpose of this study was to determine the amount of deductions imposed on social security and health insurance`s bills and its causes related to inpatients in two hospitals affiliated with Tabriz University of Medical Sciences.

Material and Methods: This was a cross-sectional study conducted in Alavi and Madani hospitals affiliated with Tabriz University of Medical Sciences by using 2015 data.  Researcher-designed checklist was used for data collecting. According to population size, census method and random sampling were used in Alavi and Madani hospitals, respectively. Gathered data were analyzed through descriptive statistics assisted by Excel v.13 software.

Results: In the studied hospitals, most of the deductions in the Alavi and Madani hospitals were related to charge of surgeon and angioplasty, respectively. Also, in Alavi Hospital among deductions factors, the most repeated one was extra application in contrary to determined tariffs. In both hospitals, the role of the human factor in cases of error cannot be denied. Extra applications, inaccuracy in registration costs and lack of knowledge of the approved insurance tariffs are the main important factors influential on the deduction.

Conclusion: Due to high rates of preventable deductions in both hospitals and being given the multiplicity and variety of services offered at the health centers, establishing income monitoring unit in hospitals and use of experienced staff is inevitable.