As for eligibility to apply and participate as a Big Brother 20 Houseguest, its the usual list of requirements. You must be at least 21 years of age at the time of application (so youll have to wait if you have an upcoming 21st bday), US citizen living in the US, not running for public office, able to pay for your own travel if a semifinalist, and available for a longer stay on their dime if youre a finalist.