I live in Michigan. My parents traveled to the USA on June 27, 2017 on a visitor's visa. They were to travel back to India on December 6, 2017, but we applied for an extension and got it approved until June 6, 2018. They are returning to India on May 12, 2018. Can they can travel back to the USA before 6 months have passed? I always heard people say the minimum period in between visits should be at least 6 months. Is that true?
Customs and Border Protection (CBP) repeatedly states that there is no set period that visitors must wait between visits. It's not necessary to wait any specific length of time before returning to the US.
However, if your visits are too long and frequent, then CBP may begin to become suspicious that you are trying to live in the US rather than simply visit. You must be able to prove, each time you enter the US to visit, that you intend to leave the US again.