Independent senator Nick Xenophon has commissioned an audit of his financial affairs after admitting he "stuffed up" by failing to declare his directorship of a company run by his father.

The SA senator says failing to disclose his role in Adelaide Tower Pty Ltd in the parliamentary register of interests in 2012 is "embarrassing" and he'll correct it.

"I'm actually undertaking an audit through my accountant, to make sure there's nothing that's been unsaid or undeclared," he told reporters in Melbourne on Friday.

Senator Xenophon says he is changing all his declaration procedures to ensure someone will independently "double and triple check" anything he needs to declare, at his own expense.

He says he was shocked it was not on the public register, and that information about his directorship was publicly viewable through an ASIC search.

Senator Xenophon joined Adelaide Tower four years ago to help his father out of financial trouble.

The company had previously owed millions in tax but the senator said he didn't have anything to do with the tax issues and his father, Theo Xenophon, had resolved the problem.

Senator Xenophon said having family dragged into the election had taken his campaign to a new low.

"He's 85 years old, I love him dearly ... I just wish he wasn't brought into this," he said.

Earlier on Friday Mr Xenophon told ABC radio "unambiguously, I stuffed up" on the declaration failure.