A loss incurred by a corporation can be carried back 5 years and forward 3 years. must be carried forward unless the company has had 2 loss years in a row: can be carried back 2 years, then carried forward up to 20 years following thgloss. cannot be used to reduce taxes in other years except with special permission from the IRS. can be carried back 3 years or forward 10 years, whichever is more advantageous to the firm.