Let’s say you discover a deduction that was overlooked on a federal tax return that has already been filed. Or you realize that you didn’t report some income. Perhaps you heard about a recently passed tax law that includes retroactive tax breaks you can benefit from.

Whatever the reason, an amended tax return may be the answer.

Amended returns generally must be filed within three years from the date you filed the original return, or within two years after the date you paid the tax, whichever is later.

However, there are exceptions to this rule. For example, when it comes to amending a tax return to claim a loss for worthless investments or non-business bad debts, for example, you have up to seven years.