Our employee was overpaid as a result of an error in payroll submissions. The amount of overpayment was not insignificant and the overpayment continued for several months (the employee apparently did not notice) before the mistake was found. When the Congregational board president approached the employee about the error the employee balked at repaying, claimed it would be a hardship to return the money and did not feel he was obligated to do so. Ultimately, after demands and threats, the employee did agree to repay the overpayment, but only after negotiating a long repayment plan that spans more than a year (and without any interest). Do Jewish law or Jewish values require that this money be returned? If so, was the employee in violation of either Halachah or Jewish values by refusing to repay the money? Should it have been returned without delay (as soon as the error was pointed out) and without stipulation? Was the Congregation in any way in error in requesting repayment? What is the proper behavior according to Jewish values and ethics?