Which visa holders are exempt from Social Security and Medicare taxes?

Wages paid to resident aliens employed within the United States by an American or foreign employer are subject to Social Security/Medicare taxes under the same rules that apply to U.S. citizens.

Wages paid to nonresident aliens employed within the United States by an American or foreign employer, in general, are subject to Social Security/Medicare taxes for services performed by them within the United States, with certain exceptions based on their nonimmigrant status. 

The following classes of nonimmigrants and nonresident aliens are exempt from U.S. Social Security and Medicare taxes:

• A-visas. Employees of foreign governments, their families and their servants are exempt on salaries paid to them in their official capacities as foreign government employees.
• • Note: Employees, attendants or domestic workers admitted under an A-3 visa may be subject to Social Security taxes unless a U.S. totalization/social security agreement provides an exemption.
• D-visas. Crew members of a ship or aircraft may be exempt if the vessel is a foreign vessel and the employer is a foreign employer, or if the services are performed outside of the United States.
• • Crew members of an American vessel or aircraft who perform services within the United States are subject to Social Security and Medicare taxes.
  • Crew members of an American vessel or aircraft who perform services outside the United States are subject to Social Security and Medicare taxes if:
  • • the employee signed on the vessel or aircraft in the United States; or
    • the employee signed on the vessel or aircraft outside the United States, but the vessel or aircraft touches a U.S. port while he is employed thereon.
• F-visas, J-visas, M-visas, Q-visas. Nonresident alien students, scholars, professors, teachers, trainees, researchers, and other aliens temporarily present in the United States in F-1,J-1,M-1 or Q-1 nonimmigrant status are exempt from Social Security / Medicare Taxes on wages paid to them for services performed within the United States as long as such services are allowed by the United States Citizenship and Immigration Services (USCIS) for these nonimmigrant statuses, and such services are performed to carry out the purposes for which they were admitted into the United States.
• • Exempt Employment includes:
  • • On-campus student employment up to 20 hours a week (40 hours during summer vacations)
    • Off-campus student employment allowed by USCIS
    • Practical Training student employment on or off campus
    • On-campus employment as professor, teacher or researcher
  • Limitations on exemption:
  • • The exemption does not apply to spouses and children in F-2, J-2 or M-2 nonimmigrant status.
    • The exemption does not apply to employment not allowed by USCIS or to employment not closely connected to the purpose for which they were admitted into the United States.
    • The exemption does not apply to nonimmigrants in F-1, J-1, M-1 or Q-1 status who change nonimmigrant status to a status which is not exempt or to a special protected status.
    • The exemption does not apply to nonimmigrants in F-1, J-1, M-1 or Q-1 status who become resident aliens for tax purposes.
• G-visas. Employees of international organizations are exempt from Social Security/Medicare taxes on wages paid to them for services performed within the United States in their official capacity as employees of such organizations.
• • The exemption does not apply to spouses and children of nonimmigrants in G status who are employed in the United States by anyone other than an international organization.
• H-visas. Certain nonimmigrants in H-2 and H-2A status are exempt from Social Security/Medicare taxes as follows:
• • An H-2 nonimmigrant who is a resident of the Philippines and who performs services in Guam;
  • An H-2A nonimmigrant admitted into the United States temporarily to perform agricultural labor.

The U.S. has signed Totalization Agreements with certain countries, which may affect an alien's liability for Social Security or Medicare taxes. The complete texts of the Totalization Agreements may be found on the International Agreements page of the Social Security Administration's website.

Wages paid for certain types of services are exempt from Social Security/Medicare taxes. Examples of exempt services include:

• Compensation paid to a duly ordained, commissioned, or licensed minister of a church in the exercise of his ministry.
• Compensation paid to a child under the age of 18 employed by his father or mother if paid under certain conditions.
• Compensation for services performed as a student nurse if paid under certain conditions.

For a list of other exempt services, refer to Publication 15 (Circular E), Employer's Tax Guide.

Source: https://www.irs.gov/individuals/international-taxpayers/aliens-employed-in-the-us-social-security-taxes