If you've used a hack or an exploit to get cash in GTA Online then your money is liable to be deleted. Rockstar is currently purging billions of in-game dollars from the game by "adjusting" accounts' bank balances.
In a support post on Rockstar's site this morning it posed itself two questions to explain to players what is going on:
Over on the GTA forums, Viper-Venom posted an image of the message you can expect if you've had your account adjusted:
Apparently, Rockstar is going after the big exploiters first. So, if you've got billions of dollars in your in-game bank account, expect to be under scrutiny.