Originally Posted by BonesCPA

Too late. The IRS and most states do not give refunds beyond three years of the original due date of the return. Assuming an April 15th due date, at this point the only years you can amend (or originally filed) and get money back are 2001, 2002 and 2003. If you owe money on a nonfiled year, their is no statute of limitations in order for them to collect the amount due. Generally, if a return is filed and an error was made but undetected by the taxing agency, they only have three years from the due date of the return to adjust you return and request the additional funds. If an amount is owed to a taxing agency, and a return has been filed, in most cases they have ten years to collect the amount due.

Bottom line, you have three years to get money back, they have much longer to collect money from you.