Prime Minister Scott Morrison is "not kidding" when he says institutions refusing to join the national child abuse redress scheme will lose public funding.
Mr Morrison and Social Services Minister Anne Ruston have threatened to cut off future funding and possibly tax concessions if organisations fail to sign up by Tuesday's deadline.
"Anne Ruston and I are not kidding. We expect people to sign up and if you don't want to sign up then I won't be signing any cheques," he told Sydney radio 2GB on Monday.
Mr Morrison and Senator Ruston on Friday wrote to 25 institutions, urging them to do the right thing and join the scheme.
"All institutions are doing in not joining is doubling down on the crime and doubling down on the hurt," they said.
"We consider it to be reprehensible that you have failed to sign up to the scheme."
The financial sanctions being considered include stopping future public funding and suspending organisations' charitable status and tax concessions.
"Be aware, failure to sign up to this program means I will ensure that there will be no further public funding that they'll be eligible for going forward," Mr Morrison said.
"I'm certainly prepared to do that and even prepared to consider their charitable status."
The Victorian government has also threatened to cut off state funding for organisations that don't join the scheme.
"Time's up," Victorian Attorney-General Jill Hennessy tweeted on Monday.
"We've already said no funding for institutions which do not sign up, and we'll explore every sanction available for those evading their responsibility to survivors."
The non-participating institutions will be named and shamed on Wednesday, when Senator Ruston announces what action the federal government will take against them.
The Jehovah's Witnesses is among the organisations that have refused to sign up, arguing it does not have the institutional settings of other faith-based institutions that the redress scheme is designed to cover.
The 25 institutions that received the letter were either named in redress applications or the child abuse royal commission, and were holding up compensation for 103 survivors.
Survivor support group Blue Knot Foundation president Cathy Kezelman said not joining the scheme was indefensible.
"Institutions which have failed to commit to joining the national redress scheme are showing that the same appalling lack of accountability and failure of moral rectitude that enabled children to be sexually abused on their watch continues unabated," Dr Kezelman said.
Religious, community, charity, education and sporting organisations have had two years to join the scheme, and must at least by Tuesday provide a written commitment to do so.
Legal service Knowmore principal lawyer Anna Swain said survivors hoped institutions did the right thing, but expected some victims would miss out on compensation and acknowledgement.
"There will be many people who are left incredibly distressed and disappointed," she said.
By mid-June, the scheme had received 7133 applications and made 2501 payments totalling almost $202 million.