A community somewhere in Australia will in 2019 become the fifth location to trial a controversial federal government welfare card.

The cashless debit card trial is also being extended until June 30, 2020, Social Services Minister Paul Fletcher announced on Friday.

But federal Labor maintains the scheme shouldn't be broadened until there is harder evidence that is helpful.

The cards - which prevent people from spending 80 per cent of their welfare money on gambling and alcohol - are already being used in Ceduna in South Australia and the East Kimberley and Goldfields in Western Australia.

The scheme is due to kick off at a fourth location - the Bundaberg and Hervey Bay region in Queensland - next month.

Mr Fletcher said a fifth location is in the government's sights for the second half of 2019, and a community that really wants the cards may get preference.

"We've got a number of communities we're thinking about," he told Sky News on Friday.

The extension of the overall trial to 2020 will provide certainty to people using the cards, he said.

An evaluation of the scheme in Ceduna and East Kimberley has found it has had a "considerable positive impact" and has been linked to a reduction in violence and harm related to alcohol consumption, illegal drug use and gambling.

But an auditor-general report released in August found the Department of Social Services' monitoring and evaluation of the trial was inadequate.

Despite that, Mr Fletcher said what the evaluation showed marries up with the positive feedback he's received from indigenous leaders, police and chemists in communities which use the cards.

"Both the formal evidence and what I've heard from people directly on the ground, strongly suggest that the cashless debit card is making a difference in communities affected by welfare-funded drug and alcohol addiction," he said.

The Greens and Labor have opposed expanding the trials, with the inclusion of Bundaberg and Hervey Bay only coming after the coalition secured a victory in the Senate.

Labor deputy leader Tanya Plibersek said although the opposition supported the initial scope of the trial, not enough evidence has been produced to justify it being broadened.

"We're open-minded, but we'd like to see more results from earlier efforts," she told reporters in Sydney on Friday.

The Greens have argued the cards won't help people get jobs or deal with addictions, instead making their lives harder and pushing them further into poverty