If you mailed Form 1040-X and did not attach Schedule D you did not attach the required supporting document.
if you e-Filed Form 1040-X, TurboTax includes all forms and Schedules.
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Regarding your original omission,
as far as I know, there is no user-selectable option to not apply a capital loss carryforward.
Your carryforward will not be depleted if your taxable income is zero; this is automatic.
@Bob in Plano
