As an example, in Oregon, the law is quite specific:

(a) A nonresident is allowed a capital loss or capital loss carryforward on the Oregon return when attributable to Oregon sources.

(b) A part-year resident is allowed a capital loss or capital loss carryforward on the Oregon return if the loss was incurred while a nonresident and is attributable to Oregon sources or if the loss was incurred while a resident.

(c) The amount of the capital loss or capital loss carryforward that is not attributable to Oregon sources may not be included as Oregon taxable income on the Oregon tax return. The capital loss or capital loss carryforward not attributable to Oregon sources cannot be used to reduce a capital gain attributable to Oregon sources.