Have a Tax Question? Ask a Tax Expert
Hi from just answer. I'm PDtax. I'll assist.
You have the latter of three years from the due date or two years from when a tax was paid to amend and get a refund of overpaid taxes.
In your example, you can still all of your 2012 overpayment back. It was due April 2013. You have at least until April 2016 to amend.
Thanks for asking at just answer. Positive feedback is appreciated. I'm PDtax.