Although the tax code contains some exceptions, income is generally taxable in the tax year received and expenses are claimed as deductions in the year paid. But “carryforwards” and “carrybacks” have special rules. In this case, certain losses and deductions can be carried forward to offset income in future years or carried back to offset income in prior years, providing tax benefits.

• Capital losses. After you net annual capital gains and capital losses, you can use any excess loss to offset up to $3,000 of ordinary income. Remaining losses can be carried over to offset gains in future years. The carryforward continues until the excess loss is exhausted.
• Charitable deductions. Your annual charitable deductions are limited by a “ceiling” or maximum amount, as measured by a percentage. For example, the general rule is that your itemized deduction for most charitable donations for a year can’t exceed 50% of your adjusted gross income (AGI). Gifts of appreciated property are limited to 30% of your AGI (20% in some cases) in the tax year in which the donations are made. When you contribute more than these limits in a year, you can deduct the excess on future tax returns. The carryover period for charitable deductions is five years.
• Home office deduction. If you qualify for a home office deduction and you calculate your deduction using the regular method, your benefit for the current year can’t exceed the gross income from your business minus business expenses (other than home office expenses). Any excess is carried forward to the next year. Caution: No carryforward is available when you choose the “simplified” method to compute your home office deduction.
• Net operating losses (NOLs). Business NOLs can be carried back two years and forward 20 years. Tip: As an alternative, you may opt to forego the carryback and instead carry the entire NOL forward.