Less than two weeks after Celeste Barber launched her bushfire fundraiser on Facebook, the campaign has raised more than $51 million.

But getting the money into the hands of charities isn't as simple as clicking the "donate" button.

Here's why the unexpectedly large amount of money raised has made things a lot more complex.

Where did the money go?

Once the money is taken from a donor's account, it goes into the PayPal Giving Fund, a registered public ancillary fund set up to distribute money to charities.

The money is not immediately passed on, with the process usually taking between 15 and 90 days.

But a spokesperson last week told the ABC that PayPal had been making special exceptions to fast-track donations made through its platform to aid in the fight against Australia's bushfire crisis.

But the money donated by more than 1.3 million people through Barber's campaign, created to benefit the Trustee For NSW Rural Fire Service (RFS) and Brigades Donations Fund, has been in limbo for days.

The bushfire crisis has attracted attention overseas, prompting international donations. ( AAP: Dan Peled )

On Thursday, a PayPal Giving Fund spokesperson said the company was "on standby" to release the funds.

Barber on Thursday said via Instagram the payout process was imminent.

"I have had some pretty long and pretty boring conversations with fancy people at PayPal, Facebook, and the RFS, and I can tell you now, your money is getting moving," she said.

But PayPal was not able to confirm the money was being distributed until this afternoon.

"PayPal Giving Fund has begun granting funds to The Trustee for NSW Rural Fire Service and Brigades Donation Fund," a spokesperson told the ABC.

Where will the money end up?

"PayPal Giving Fund's first priority is to honour the donors' wishes and grant donated funds to the charity they've nominated — which in the case of Celeste Barber's fundraiser is the Trustee of NSW RFS to whom funds are being granted," the spokesperson said.

It is unclear how that money will be spent, but an RFS spokesperson said members would be consulted on how best to spend it.

RFS Commissioner Shane Fitzsimmons last week told The Guardian the service wanted to understand the intention of people making donations.

"Was it to go to disaster victims, was it to go to make better arrangements and better conditions for volunteers?" he said.

"We will need to target the money to where people intended it to go."

Barber's campaign attracted more than 1.3 million donors. ( Twitter: @celestebarber_ )

What do donors want?

Australian National University Associate Professor Michael Eburn, who wrote about the fundraiser in his Emergency Law blog, said there was confusion among donors about where the money was going.

"There is no suggestion that the RFS don't deserve the money or won't use it well," Dr Eburn told the ABC.

"The only concern, reading the comments of the donors, is that some don't understand who or what they have donated to."

Some donors commented on the fundraiser page asking whether the money raised would be split between charities and firefighting services.

Barber set up the fundraising campaign with an initial target of $30,000 after her family in Eden, NSW was affected by bushfires.

She did not set up her campaign for it to be an Australia-wide, all-encompassing fundraiser for the bushfire crisis.

But as the campaign went viral, it came to be viewed as a national fundraiser by some, particularly those from overseas.

PayPal's spokesperson said the platform was fast-tracking donations made to the bushfire crisis relief effort. ( AAP: Dan Peled )

International donors unfamiliar with Australia's state-based firefighting services may have assumed the fund was for a national fire organisation or for victims, but Mr Eburn said Barber was not misleading people.

The page clearly states the RFS Trust was the intended recipient of the funds.

Barber's fundraiser makes no mention about other states, victims or wildlife in her brief campaign description that reads: "Please help anyway you can. This is terrifying."

The fundraiser was created for the benefit of the RFS. ( Facebook: Celeste Barber )

"She set up a page and asked people to donate to the RFS Trust and they did," Dr Eburn said.

But as the final tally grew, so did demands for the money to be split up.

More money, more responsibility

While Barber's initial target of $30,000 would not have left charities with much if it was split up, even a small percentage of the $51 million would be quite a large donation.

"It seems with raising a f***-tonne of money comes with a f***-tonne of people telling you what you should do with it," she said in an Instagram story last week.

Barber set out to raise $30,000 but her campaign has attracted more than $51 million in donations. ( ABC News )

"So it's going to the RFS and it will be distributed out.

"So I'm going to make sure that Victoria gets some, that South Australia gets some, also families of people who have died in these fires, the wildlife.

"I get it, I get it all, I'm hearing you all. I want you to know that, otherwise why raise this money if it's not going to go to the people who absolutely need it."

The ABC contacted Barber to clarify what she meant by this, but her publicist said she was declining interviews and would instead be "keeping everyone updated via Instagram".

Can the money be divvied up?

Possibly, but it would not be a simple process.

There are limited ways the RFS fund trustees can spend the money, as they are bound by their trust deed which states the funds should be used:

…to or for the brigades in order to enable or assist them to meet the costs of purchasing and maintaining fire-fighting equipment and facilities, providing training and resources and/or to otherwise meet the administrative expense of the brigade which are associated with their volunteer-based service activities.

Dr Eburn said, as it stands, the deed makes it "impossible" to distribute money to anyone other than RFS brigades.

"To move the money elsewhere may require an Act of Parliament or approval of the NSW Supreme Court," he said.

However, Swinburne University Industry Fellow Krystian Seibert shared a theory from a charity lawyer about how the trust fund could spread the money around.

It would need to be shut down once the money came through.

The "winding up of the Trust" clause says money left in the account has to be distributed to other registered charities as nominated by the trust. This would free up the trust to donate the Barber fundraiser money to other causes.

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Then they could set up a new charity to replace the RFS Donations Fund, distributing some of the $51 million to the new entity for NSW volunteer firefighters, Mr Seibert said.

"I don't know how likely this would be," he said.

"But it is another option to address the legal issues which have arisen.

"I do think that fundraising websites need to give consideration as to whether they are sufficiently clear about how the arrangements they use work, so people setting up fundraisers, and donors themselves, are fully aware of them."