Don't Mess With Taxes

If you just discovered an error on an old tax return, you might be able to correct it.

All you need is Form 1040X … as long as the mistake was made on a return you filed within the last three years.

Click image for PDF download of full Form 1040X.

Details on filing an amended tax return, which is what you'll do with Form 1040X, are found in the Weekly Tax Tip.

I'll let you check out the full tip at your leisure, but here are five key things to keep in mind.

First, note the three-year time limit to file an amended return. Generally, if you want to collect a credit or refund based on your amended return information, you must file Form 1040X within three years, including extensions, of the date you filed your original tax return. For most people, this means that returns for tax year 2011 or later can still be amended.

Second, be prepared to show the Internal Revenue Service what items you originally reported, what changes you are making and why you're doing so.

Third, you'll have to file a paper Form 1040X. The IRS plans to make amended return filing electronic, but it's not there yet. So send in the paper form and expect to wait up to 12 weeks for it to be processed. Three weeks after send in your 1040X, you can check what's up with it via the IRS' Where's My Amended Tax Return? online tracking tool.

Fourth, if you file an amended federal tax return, you might need to make changes to a previously filed state return.

Fifth and finally, even if making changes to your original return costs you money, you should file a Form 1040X. By doing so, you'll stop any penalty and interest charges that the IRS will add when it finds the mistake. And changes are the tax man will eventually find your mistake.

Form 1040X for same-sex married filers: The IRS says it's expecting almost five million taxpayers will amend their returns by the time 2014 ends.

The tax agency also reminds same-sex married couples that they may want to consider filing amended returns.

Remember, following the Supreme Court ruling striking down a portion of the Defense of Marriage Act, or DOMA, the IRS ruled that it would recognize legally-married same sex couples as married for all tax purposes. This is true regardless of marriage laws in the state where the couple lives.

For returns originally filed before Sept. 16, 2013, the IRS notes that legally married same-sex couples have the option of filing amended returns to change their filing status to married filing separately or married filing jointly.

But this is just an option. Even if a same-sex spouse finds he or she needs to send in a Form 1040X for another tax reason, her or she is not required to change filing status on a prior return. In either case, their amended return must be consistent with the filing status they have chosen.

So if you need to fix an earlier filing mistake, to claim some tax breaks you overlooked or to change your marital tax-filing status to take advantage of some tax benefits, check out Form 1040X.

You also might find these items of interest:

• What to do if your tax refund is wrong
• Tax tips for same-sex married couples new to filing together
• Missed the tax deadline? Quit making excuses for not filing and take these three steps now