The former Australian Trucking Association board member has authorised material published by lobby group Defenders of Self-Funded Retirees.

Mr McMillan’s name is on a document which declares “Bill Shorten’s Labor Party has promised to steal $5.2 billion a year from self-funded retirees by denying access to dividend imputation credits”.

It then states “this envy driven tax grab amounts to $6200 a year ripped off from each targeted self-funded retiree”.

The Defenders are managed by Liberal Party ACT Senate candidate Robert Gunning and they campaigned against Labor in last year’s Longman by-election.

But Mr McMillan said his motivation to oppose Labor’s cash refunds for excess dividend imputation credits was driven through his concerns for self-funded retirees and his experience in having been a trustee for a transport industry superannuation fund.

“I’m not a front for any party,” he said.

“I’m not a Liberal Party member and who I vote for is my own business – I’m a normal person on the street.”

Mr McMillan described the Labor Party’s policy as “bloody criminal”.

Labor Treasury spokesman Chris Bowen says the concession’s “welfare for the wealthy” and the policy has let individuals and superannuation funds “receive a cash refund from the ATO if their imputation credits exceeded the tax they owed”.

Mr McMillan said the policy rewarded those who had been smart investors and compared it to investing in solar panels and receiving long term benefits.

“I’m just surprised it’s a big deal,” he said.

“It should never have happened and we should be jumping up and down.”

Labor asked the Australian Electoral Commission to probe the Defenders over no authorisation on webpages.

The AEC has contacted the Defenders “because the organisation appears to have distributed paid advertising on Facebook that contains ‘electoral matter’”.

It has been asked to authorise the material to comply with transparency and accountability requirements.