IRS issues temporary and proposed regulations (T.D. 9571, REG-113903-10) providing guidance on the allocation and apportionment of interest expense by corporations owning a 10 percent or greater interest in a partnership. The regulations propose to revise Treasury Regulations Section 1.861-9T(e)(2) to clarify that a corporate partner with a 10 percent or greater interest in a partnership must allocate its direct interest expense to all of its assets, including its proportionate share of partnership assets. The guidance also addresses the allocation and apportionment of interest expense using the fair market value method, and reflects legislative changes to the tax code related to foreign corporations treated as affiliated groups.