I know the international students (F1-visa) are limited when it comes to work (max 20 hours/week on campus job).
However, are they allowed to have other sources of income in US? Is renting his/her apartment a legal way to earn income?
To my understanding, foreigners can own real properties in the United States. Therefore, they can legally rent out for a profit as income (notice legally). When those foreigners (aliens) study in the United States on F-1 Visa, I believe, they can still rent out their real properties pursuant to applicable laws. And it's not considered as employment as far as USCIS is concerned, because based on USCIS Definition of employment,
The term employment means any service or labor performed by an employee for an employer within the United States, including service or labor performed on a vessel or aircraft that has arrived in the United States and has been inspected, or otherwise included within the provisions of the Anti-Reflagging Act codified at 46 U.S.C. 8704, but not including duties performed by nonimmigrant crewmen defined in sections 101(a)(10) and (a)(15)(D) of the Act. However, employment does not include casual employment by individuals who provide domestic service in a private home that is sporadic, irregular or intermittent;
Similarly, subletting should be acceptable as long as it's legal pursuant to applicable laws. For example, subletting usually needs the approval of the property owner. Otherwise, subletting illegally will negatively impact the good standing F-1 status.
P.S. I am NOT attorney. This post is NOT legal advice.
i would like to express my two cents. if you check out SCHEDULE E (Form 1040). you would realize, if you own the property, then the rental income is passive income which is not employment, it would be legal for your F1 visa. how to operate: fill up this form, have a number then fill in line 18 in the 1040NR. and you will be all set. but i am not sure if you rent the place and sublet. it would be hard to fill this form.