very simple rainday. you had say 20k in non taxed money, you invested it in a single premium bond for say 5 years, you got the money back + what ever it had grown to at the end of 5 years, tax paid on the returns inside in the fund, some times this dirty money was brought back in as clean money the person stating it was as a result of bond etc, othertimes left to roll over again and again. NIb had this system that made the news a few years ago. At the time the dirt investigation started I said this would be next and would give a fair guess as to which companies will end up as top of the league for most of these in particular order- IL, aib, boi.