it also depends on the resident state.  If the resident state is a high tax state, and the loses pertain to a low tax, non-resident state, who cares?  Why file if you do not have to.  You don't care about carrying forward a loss, because when you ultimately pay tax to that state in a future year, you'll get a credit against the home state that is equal to what you pay, or pretty close to equal.  Again, as long as the resident state is a higher tax rate, you have no worries.