(a) Part II (section 1311 and following), subchapter Q, chapter 1 of the Code, provides certain rules for the correction of the effect of an erroneous treatment of an item in a taxable year which is closed by the statute of limitations or otherwise, in cases where, in connection with the ascertainment of the tax for another taxable year, it has been determined that there was an erroneous treatment of such item in the closed year.

(b) In most situations falling within this part the correction of the effect of the error on a closed year can be made only if either the Commissioner or the taxpayer has taken a position in another taxable year which is inconsistent with the erroneous treatment of the item in the closed year. If a refund or credit would result from the correction of the error in the closed year, then the Commissioner must be the one maintaining the inconsistent position. For example, if the taxpayer erroneously included an item of income on his return for an earlier year which is now closed and the Commissioner successfully requires it to be included in a later year, then the correction of the effect of the erroneous inclusion of that item in the closed year may be made since the Commissioner has maintained a position inconsistent with the treatment of such item in such closed year. On the other hand, if an additional assessment would result from the correction of the error in the closed year, then the taxpayer must be the one maintaining the inconsistent position. For example, if the taxpayer deducted an item in an earlier year which is now closed and he successfully contends that the item should be deducted in a later year, then the correction of the effect of the erroneous deduction of that item in the closed year may be made since the taxpayer has taken a position inconsistent with the treatment of such item in such earlier year.

(c) There are two special circumstances which fall within this part but which do not require that an inconsistent position be maintained. One of these circumstances relates to the inclusion of an item of income in the correct year and the other relates to the allowance of a deduction in the correct year. In the first situation, if the Commissioner takes the position by a deficiency notice or before the Tax Court that an item of income should be included in the gross income of a taxpayer for a particular year and it is ultimately determined that such item was not so includible, then such item can be included in the income of the proper year if that year was not closed at the time the Commissioner took his position. In the second situation, if the taxpayer claims that a deduction should be allowed for a particular year and it is ultimately determined that the deduction was not allowable in that year, then the taxpayer may take the deduction in the proper year if that year was not closed at the time the taxpayer first claimed a deduction.