I'm a Canadian, currently residing in Taiwan, and I was working as a consultant for Deloitte in 2015 while in the USA on a TN visa. My employer withheld FICA tax even though I was non-resident and refused to give it back and said I needed to go through the IRS to get it refunded. My accountant submitted form 843 on my behalf for a FICA refund for FY2015, and I got several letters from the IRS saying another 45 days is needed to figure out what to do, but it's been several months since I've heard from them now. I've called he number on the form (800-829-0922) and all the IRS reps are clueless, saying FICA is not a regular income tax and doesn't even appear on the system they are using, and they aren't even able to redirect me to someone who can help. I've been waiting for over 2 years for my refund and it's been more than 6 months since I heard from the IRS saying they needed more time. My accountant, who filled for the refund has stopped responding to my calls and emails. What can I do?