(a) In general. The determination of an item after it has become a nonpartnership item with respect to a partner is not controlling in the determination of that item with respect to other partners. Thus, for example, the determination by a court in a separate proceeding relating to a partner that a certain partnership expenditure was deductible does not bind either the Internal Revenue Service or the other partners in a later partnership or other proceeding.

(b) Effective date. This section is applicable to partnership taxable years beginning on or after October 4, 2001. For years beginning prior to October 4, 2001, see § 301.6231(e)-1T contained in 26 CFR part 1, revised April 1, 2001.