About 88 per cent of the blocks are bigger than 700 square metres, the minimum allowed for subdivision or unit-title development, the Government says.

Unit titles are separate titles, but have shared areas, such as driveways. Fluffy owners will still be able to buy back their full blocks, but they will cost significantly more given the ability to develop it as two titles.

Unit titling would not be pursued in heritage precincts, the taskforce said.

Chief Minister Katy Gallagher acknowledged that the desire of Fluffy owners to return to their blocks and rebuild was one of the strongest reactions as details of the scheme have emerged. Home owners want their land back at the current unimproved value.

But Ms Gallagher said any further subsidies would make the scheme unaffordable. It is already expected to leave the Government $300 million to $500 million out of pocket, depending how much it can recoup from the sale of blocks.

"I don't want to characterise it as generous but I think it is fair," she said.

"If we were further subsidising, ie "we'll purchase your house at more than it's worth so you can build back what you've currently got and the sale of the land at what it's currently valued at", that net-cost figure just escalates exponentially and ... it means there would be no scheme, because it would be unaffordable.

Owners who want to buy their land will have to wait until the government is prepared to release the block back into the market, with advice that the market could absorb 200 Fluffy sales a year, Ms Gallagher said.

The taskforce has told owners that the staging of the demolitions and the schedule for land release meant "it may be a number of years before a particular block becomes available for resale".

Ms Gallagher said she had no doubt people would resist the mass buyback, but she was focused on encouraging as many people as she could to take up the offer. She was open to considering any "genuinely good ideas" but any refinements would be at the edges, she said.

One group of Fluffy owners will be able to keep their land - the handful who took matters into their own hands and demolished in recent months. They will be refunded the cost of their demolitions, paid for the cost of the houses they demolished and allowed to keep their land. But Ms Gallagher said it would be wrong to paint anyone as a winner.

The Government is offering all Mr Fluffy homeowners a stamp duty concession on their purchase of a new house. Stamp duty is not being waived outright, but will be waived to the value of whatever stamp duty their current house would attract if it were sold.

But homeowners face a number of other complications outside the control of the ACT Government, including early repayment fees changed by banks on mortgages, capital gains tax, eligibility for aged pensions and other pensions after they receive a lump sum for their home, connection fees for electricity and other utilities, and the loss of generous solar feed-in tariffs when they move homes.

The ACT Government is writing to the banks, the Commonwealth, the Tax Office, and ActewAGL and other utility providers asking them to waive fees and recognise the situation of Fluffy owners.

Asked about the Commonwealth's insistence it had no legal liability, despite a signed memorandum of understanding from 1991 saying it would share costs of any further clean-up, Ms Gallagher said the memorandum was not legally enforceable but she had hoped it would put moral pressure on the Commonwealth. If the ACT had pursued the question of legal responsibility, the Commonwealth would have fought the claim, the dispute would have dragged out and the territory would not have been guaranteed to win, she said.