The most senior member of staff at a Sydney council spent more than $400,000 a year on corporate credit cards, received twice monthly payments for no known work and once had his $70,000 annual super "top-up" hand-delivered in cash, a corruption inquiry has been told.

The allegations against Botany Bay Council's former general manager, Peter Fitzgerald, count among a series aired during an extraordinary 30 minutes of testimony before the Independent Commission Against Corruption late on Friday.

Council's former chief financial officer, Gary Goodman, the inquiry's principal person of interest in the alleged theft of more than $4.2 million in council funds using fake invoices since 2009, began his long-awaited evidence an hour after the ICAC hearing was scheduled to finish sitting for the week.

He agreed decisions by senior staff at the council went unquestioned for two decades.