Here's my story...

Entered US in 2008 at F1. Graduated in 2013. Began work at 2 jobs at OPT in August 2013. Job 1 deducts Medicare, but is SS exempt due to state pension plan. Job 2 deducts FICA, but I tell them I'm exempt as F1 OPT (as was my understanding). For tax year 2013 I file for Closer Connection Exemption, and it's granted.

For 2014, job 2 continues to deduct no FICA. I continued work in US after OPT on TN1 status. Doing my taxes, I call Revenue Canada to figure out my tax residency. Based on their advice (they are continuing to investigate), I am not a tax resident of Canada for 2014. Which means I will file as a resident alien in the US (regular 1040). Now I need to pay the back FICA from job 2. My share is under 2k and I do have the money and am willing to pay. I need to know how to proceed - do I contact my employer or the IRS?

I should add that Job 2 refunded the FICA after the first month, then did not deduct any more.