The "Mulligan" rule, or "do-overs," allows taxpayers to amend their original tax returns when they first files an original return and later seeks to change it. This is a "superseding" return, which cancels out the original and replaces it. The most common method of changing a return is an amended return, filed on IRS Form 1040-X in New Mexico. To qualify as a superseding return, the return must be filed before the due date of the original return, including any extensions, and can be filed any time up to Oct. 15. However, if you are eligible for a supersing return, it is not required to file an eligible return. The practice practice of Jim Hamill, director of Reynolds, Hix Co & Co in Albuquerque, can be reached at jimhamill@cococ.