We are opening a new administrative office, for operations staff, with no depositary functions. Do we need to notify anyone of the opening, beyond sending a letter to our state and federal regulators?

We are not aware of any additional steps that you would have to take before opening an administrative office, provided that no “deposits are received or checks paid or money lent” at the office. (See definition of “domestic branch” under the FDIC Act, 12 USC 1813(o).)