"Taxable plan distributions would be taken into account in determining whether the AGI threshold is met .... Logically, the same result should obtain for most but not all equity-based compensation arrangements. For example, dividends received after a section 83(b) election is made with respect to a restricted stock award may be subject to section 1411.... In contrast, the taxable portion of annuity payments or withdrawals from and surrenders of nonqualified annuity contracts -- i.e., annuity contracts purchased outside of qualified retirement plans, commonly to accumulate retirement savings -- would be 'investment income' for this purpose[.]"  MORE >>