Answer:
Taxable gain is $5,000 in the current year.
Explanation:
The section 1231 says that the unrecaptured losses in trading can be carried forward for a forseeable future to set off these losses against trading gains to decrease the tax liabilities. Hence the net gain that is taxable is calculated as under:
Taxable Gain = $18,000 - $13,000 = $5,000