Rental income tax for international buyers

[Henry Li]

Hi, 

   I had several international buyers who were travel visa holder. They purchased some rental properties here in Mass. I heard that the first three years are tax free. First of all, is this true? Secondly, what about after the three years? Do the investors file tax return? they don't have any other income in the U.S. And they don't even have a social security number. Even if they want to fix a tax return, the problem is how? any insight ? thank you