As a tax preparer, my responsibility goes beyond filling out the information required on each form in the return. I feel it is important to also be sure that all deductions that can be taken are included in the return, that the correct information is being reported even if that means extra research to figure out what is needed, like the cost basis for stock or mutual fund sales. For proper cost basis that might include having to search the internet or call brokers to find the history of the purchases that a client made in the stock or fund for which they have lost that information over the years. For items on Schedule A, Itemized Deductions, it might involve helping a client develop the documentation to support the amount to claim each year.