When you make a Non-Deductible Traditional IRA Contribution, you need to include Form 8606. If you forgot to file it with your return, you can send it in separately now. If you made the Traditional IRA Contribution for Tax Year 2014, you should file a 2014 Form 8606.
Here is a link to the 2014 Form 8606: https://www.irs.gov/pub/irs-prior/f8606--2014.pdf
Here is a link to the 2014 Form 8606 Instructions: https://www.irs.gov/pub/irs-prior/i8606--2014.pdf
