Accountants can make errors because they are dealing with numbers and money and partly because they make predictions or projections of costs like cost estimates based on the most likely expenses of a project but a project can be complicated and hard to predict everything so unexpected costs can come up. Because they are dealing with numbers and usually many calculations and sometimes quite involved figures, and they are human, it can be easy to overlook certain things. The mistakes need to be corrected so that plans can be made based on solid economic and financial data as false data can make a project either look very good or very bad and so can lead to erroneous decisions that can affect the lives and finances of a lot of people.
