If you need to make a change to any return you have sent us, do not file another return for that year. You should wait until you receive your notice of assessment before requesting any change to a return that has not been processed.
You can only request a change to a return for a tax year ending in any of the 10 previous calendar years. For example, a request made in 2012 must relate to the 2002 or a later tax year to be considered.