AMENDMENT

[hasanfaisal]

"Tom filed his 2013 tax return on march 15, 2016. he realized he missed a refundable credit. if he amends his return now will he be able to get his refundable amount he missed?"

[DoninGA · Accepted solution]

No.  A tax return has to be filed within three years from the original due date for a tax refund.  

Go to IRS Form 1040X instructions - https://www.irs.gov/pub/irs-pdf/i1040x.pdf

Generally, for a credit or refund, you must file Form 1040X within 3 years (including extensions) after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later

For tax year 2013 the tax return or the amended tax return with a tax refund, without extension, had to be filed on or before April 15, 2017.