FinCEN has not said that allowing continued access to a safe deposit box because of a rent payment is a new account, and I would be very reluctant to suggest that it might be. A safe deposit box lease agreement is the equivalent of a "month-to-month" apartment rental. You keep paying the rent and your key continues to work. For the box, you keep paying the rent and you get access for the next billing period. It's not a new account.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8