Axiomatically, you sign your federal income tax return under penalties of perjury. That means it should be accurate and complete. But in the real world, despite your best efforts and honesty, you may forget something or make an innocent--even if foolish--mistake.

In fact, it may not even be your fault. You may receive a Form 1099 or Form K-1 after you file your return. Amended K-1s from partnerships, S corporations and LLCs have a particularly bad habit of showing up right after you file.

In such cases, it may surprise you to learn that you are not required by law to file an amended return. Once you have filed your tax return, you cannot be prosecuted for failing to file an amended return, even if something happened after you filed that makes it clear your original return contains mistakes. When considering an amendment, first ask yourself whether the return you filed was accurate to your best knowledge when you filed it.

If it was, you are probably safe in not filing an amendment. (You still may want to amend, of course, but filing an amendment would be optional.)