The Finance Department is responsible for maintaining the City's accounting and financial systems including accounts payable, accounts receivable, payroll, investments, fixed assets, utility collections and occupancy tax collections. The department is also responsible for risk management, purchasing, and municipal court for the City.

The City of Seguin Finance Department has been awarded a Certificate of Achievement for Excellence in Financial Reporting by the Government Finance Officers Association of the United States and Canada (GFOA) for the City's comprehensive annual financial reports for fiscal years ending September 30, 2008 to 2021. The Certificate of Achievement is the highest form of recognition in the area of governmental accounting and financial reporting, and its attainment represents a significant accomplishment by a government and its management.