Advancements in technology have significantly reduced the risk of tax preparation errors, but not all of them. While some of the items below seem obvious, even the most seasoned CPAs and tax professionals have been known to commit these tax preparation no-nos. Whether you are a 20-year accounting veteran or just entering the field, it behooves you to keep a list (and check it twice) of the most common tax preparation blunders. Based on Bloomberg Tax Accounting’s in-depth research, here is a partial list of the common mistakes in tax preparation.