Any rules or restrictions on a Basic Income plan are a bad idea because checking and enforcing those rules needs a big bureaucracy with investigators and enforcers. I can see an immediate cheat already of just working off the books for cash, thus being "unemployed." More than a third of the US economy is already untaxed cash transactions. (Seriously, who pays teen babysitters in anything but cash? And do you think that they track it and pay taxes on it?) No need to make it more.
Just pay everyone the exact same amount and save all the money you'd otherwise spend on making rules.