Making a traditional IRA contribution after filing taxes?

[Ricky]

I filed my taxes last month. I know I can still contribute to an IRA until the tax deadline. The question is, if I contribute, can I claim 2014/2015 contributions together on next years tax forms? Or would I have to amend my return if I wanted to claim contributions up until April 15th?

I don't have a retirement plan at work so it would be fully deductible.

[MustachianWays]

You would need to file a 1040X to amend your filed return. I did it last year but it was because I recharacterized a Roth contribution as traditional. I think the deadline to file an amended return is October. Just know that your refund will take quite a while to show up. Took about 3 months for me.