You need to report the loss in the year it was sold.
Then if there is a capital loss of over $3,000 with no other capital income to offset, it will automatically be carried over to 2018.
A capital loss carryover is the net amount of capital losses that aren't deductible for the current tax year but can be carried over into future tax years. Net capital losses (total capital losses minus total capital gains) can only be deducted up to a maximum of $3,000 in a given tax year.
