Don’t like to admit your mistakes? Get over it.

When it comes to taxes, simply saying ‘I’m sorry’ just won’t cut it.  You may need to make amends.

We learned in school that “X” means “wrong;” the same goes with tax returns.

If you made a material mistake on a tax return from prior years, you need to file a Form-1040X to report the errors you made on the original Form-1040.  If you have more than one erroneous 1040–which can happen easily if your mistake carries through more than one year–you must file a separate 1040X for each year.  It may sound creepy, but these X-files have to be mailed.  There is no e-filing for wrongdoers.

Fortunately for those of us who are merely math-challenged or just forgetful, an amended return is not always necessary. If the error is simple addition or subtraction or a missing supporting form, such as your W-2, just sit tight.  The IRS often spots these errors and takes a “Don’t call us, we’ll call you” approach.

Wait until you get the IRS notice of the minor error to make good. If you initiate the reporting, you may find yourself in a situation not unlike trying to talk to someone on a cell phone with a really bad, delayed connection.  You speak, the IRS speaks, without either of you first hearing what the other one has to say. You will want to hang up in frustration, but in this case, you can’t.

When your mistake involves incorrect numbers, and those numbers are not in your favor, you definitely should amend, and the sooner the better.  If you misreported your filing status, your income, your deductions, or your credits, and the correct information results in your owing more taxes, get cracking on that 1040X to stop the accrual of any penalties or interest resulting from the mistake.

What about a situation where “my bad” means “my good?”  Sometimes omissions can result in a refund, and you might think this, too, is reason to hustle.  Not so fast.  If you use an accountant to file all your tax returns, weigh the cost of the accountant’s time to fill out the 1040X.  Tax returns are never as simple as they purport to be, and you may find you are paying every bit of the resulting 1040X refund, and more, back to the accountant.

Sometimes an amended return is in order even when no mistake has been made.  For example, there are tax provisions that allow certain current losses to be carried back to previous years to offset past taxable income.   There are also situations where new tax law is enacted, seeking to benefit certain types of taxpayers such as homeowners, hurricane victims, or veterans, and the way for these groups to collect the benefits is by amending their returns.

The latest retroactive example comes in President Obama’s 2009 American Recovery and Reinvestment Act, which allows first time homeowners to get an $8,000 credit for homes purchased between January 1, 2009 and December 1, 2009.  The credit can be applied to either the 2008 or 2009 return. Read more here.

For those taxpayers who qualify because of a first time home purchase made after their 2008 returns were filed, and you wish to apply the credit to 2008, an amended return is necessary.

If the idea of filing a 1040X fills makes you tremble, take heart. When we do anything repeatedly, such as walking, talking, or paying taxes, we are bound to trip up eventually.