I spoke to a CPA about my 2015 tax situation. I had a job in 2015, but I also had stock trading losses that exceeded the salary that I received from the job. The CPA said that I traded enough that it can be considered a business, which means I can file a net operating loss that I can carry back to a few years ago when I had trading gains. He said that if I do that, then I will have no income for 2015, and I will get a refund for the taxes that were withheld in 2015.
I'd like to clarify exactly which taxes that were withheld I would get a refund on. (I have not decided to hire him yet as his fees are very high, and I don't want to pay him for additional time to ask this one question, so I'm asking it here.) Let's say hypothetically that I made $60K last year in salary from the job, and had $12K in federal income tax withheld, $3K in Social Security tax withheld, and $1K in Medicare tax withheld, and that I had $75K in trading losses. If I file an NOL, will the tax refund only include the $12K in federal income tax that was withheld, or will it also include the $4K in Social Security and Medicaid taxes that were withheld?