You have up to three years after the date you filed your original return to claim an overlooked write-off. Thinkstock By Kimberly Lankford, Contributing Editor March 13, 2015 When I was filing my taxes this year, I discovered that I could have qualified for the American Opportunity Credit for my daughter's college tuition in 2012 and 2013, too. Is it too late to claim this credit for those years?See Also: 8 Places to Find Free Money It's not too late. You have up to three years after the date you filed your original return to file an amended return and get a refund for the extra credit. It can be worth the effort: The American Opportunity Credit is worth up to $2,500 per student for each of the first four years of college (see Don't Miss Out on This Credit for College Costs for more information). You'll need to submit Form 1040X, enter the year of the return you are amending, fill in the new numbers and attach any tax forms that are affected by the change (you'll need to include Form 8863 for the American Opportunity Credit). You must file a separate Form 1040X for each tax year you are amending and mail each year's amended return in a separate envelope (you can't file an amended return electronically). For more information, see the IRS's Amended Returns. It can take up to 16 weeks for the IRS to process your amended return. You can check on the status using the IRS's Where's My Amended Return? tool starting three weeks after you mailed your amended return. You'll need to provide your Social Security number, birth date and zip code. Advertisement Reducing your federal tax bill could also lower your state income tax bill. File your amended federal return first, and get a copy of the transcript of your account from the IRS confirming that you amended your federal return (see the IRS's Get Transcript page to order the transcript). Then file an amended return with your state along with a copy of your federal Form 1040X. To check for other tax breaks that could get you back even more money, see The Most-Overlooked Tax Deductions. Got a question? Ask Kim at firstname.lastname@example.org.