I am an international student. I am not supposed to pay SSN/Medicare tax as per IRS. But I payed them in 2020. What should I do get them back?

[mharsh02]

I asked my employer to take those taxes out of my pay, but since they did not want any trouble, they kept charging me.

[JohnW152]

You'll need to file Form 843 with the IRS to claim a refund. 

Please see the IRS page Social Security Tax / Medicare Tax and Self-Employment for a description of the procedure.

When social security or Medicare taxes were withheld in error from pay that isn't subject to social security and Medicare taxes, you must first contact the employer who withheld the taxes for a refund. 

If you can't get a full refund of the amount the your employer, you need to file a claim for refund on Form 843, Claim for Refund and Request for Abatement.

[Opus 17]

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@JohnW152 wrote:

You'll need to file Form 843 with the IRS to claim a refund. 

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Note that this form is not part of a tax return and is not supported by Turbotax.  You will file it separately on your own. 

[Opus 17]

Actually, you may need to step back and think about this a bit.  You are only exempt from social security and medicare on wages that are related to your status as a student or scholar.  There is a summary here,

https://www.irs.gov/individuals/international-taxpayers/foreign-student-liability-for-social-securit...

Any organization that sponsors J or F student or scholar visas should be equipped to not charge employment taxes.

So I wonder if this was a second job, outside income, side job, etc. that is not related to your status as a international student or scholar.   In which case, you are not exempt for those wages.