1.809-9—Computation of the differential earnings rate and the recomputed differential earnings rate.
(a) In general.
Neither the differential earnings rate under section 809(c) nor the recomputed differential earnings rate that is used in computing the recomputed differential earnings amount under section 809(f)(3) may be less than zero.
(b) Definitions—
(1) Recomputed differential earnings amount.
The recomputed differential earnings amount, with respect to any taxable year, is the amount equal to the product of—
(2) Recomputed differential earnings rate.
The recomputed differential earnings rate for any taxable year equals the excess of—
(c) Effective date.
The regulations are effective for all taxable years beginning after December 31, 1986.