The organisers of a forum urging council de-amalgamation in the former Douglas shire in far north Queensland say they are expecting a big turnout tonight.

The community will vote next month on whether to split from the Cairns Regional Council.

Robert Hanan from the Friends of Douglas Shire says conflicting claims about the benefits and costs are confusing residents.

"They are very engaged by the issue and they are a bit confused," he said.

"As you know, we've been fighting this for five years and I think the opposition's problem is they're now finding they've got to do all of this in the last few weeks."

A Queensland Treasury report says de-amalgamation would cost Douglas ratepayers more than $2,000 in the first five years and the resulting council would have a high chance of financial failure.

However, Mr Hanan says that report is flawed.

"What they did was they built a financial scenario based on the cost of doing business by Cairns Regional Council," he said.

"Now they're much bigger, more bureaucratic and their costs of doing business are significantly greater than a smaller shire, so we've based our model on how the shire was operated before."

Tonight's forum will be held at the Mossman Shire Hall at 6:00pm (AEST).

Another forum will be held in Port Douglas next week, before a local referendum in March.

Meanwhile a former Rockhampton mayor is urging residents of the former Livingstone Shire to vote NO to de-amalgamation.

Residents will cast a vote next month on a proposal to break away from the Rockhampton Regional Council.

Brad Carter says a split may give more local representation but there are dangers the smaller council will be financially weak.