With the implementation of the National Health Insurance (NHI) which gives payments of a fixed sum of budget to medical services, hospitals pay much attention to their accounting system. Thus, for the interests of patients and managements of hospitals, nurses must not only make an effective way to calculate, but they also have to execute the standard of calculation accurately and to inspect the completion of the calculation periodically. Our survey shows that up to 67% of our nurses, in wards of internal medicine, are not aware of the contents of calculation for common treatments. This results in a low completion rate of 79.96% for nurses to carry out the standard of calculation. The two main reasons for the incompletion are neglect of calculation (52.1%) and miscalculation (41.02%). Half of the nurses who miscalculated neglect or miscalculate because they do not understand which of the treatment items should be calculated. 30% of them think the treatment items are not be calculated, so they neglect the items. Therefore, we set up a standard for completing calculation of treatment and we issue a reference book for calculating common treatments in wards of internal medicine. We hope that nurses will understand 99.5% of the contents of calculation for common treatments and 100% complete the standard for calculation.