Answer:
The 2018 loss was carried forward and decreased the corporation's tax liability during 2019. The 2020 loss should also be carried forward to offset any future gains and reduce future tax liabilities. A company can carry forward a loss indefinitely, since it is allowed to deduct a maximum of 80% of a future year's net income.
If this was an S corporation, it would be pass through entity that is not taxed directly, instead, the owners are taxed. Therefore, this $21,000 loss will be distributed proportionally among all the stockholders, and they must deduct their taxes independently.