Asylum seekers were submitting the paperwork needed to claim protection in line with the government's preferred time frame even before Peter Dutton sensationally threatened to boot them out of Australia.
The immigration minister has given more than 7000 asylum seekers with outstanding applications a non-negotiable cut-off date of October 1 to "lodge it or leave."
However, immigration department boss Michael Pezzullo says 6000 applications were submitted in the past six months, and at that rate, all outstanding lodgements - bar some possible exceptions - will be in by October.
Greens senator Nick McKim pressed Mr Pezzullo at a Senate hearing in Canberra about the point of the deadline if this was his department's view.
"Just to make sure that we keep the run-rate going," Mr Pezzullo said on Tuesday.
Senator McKim then turned his attention to cabinet minister Michaelia Cash, who said the policy objective was crystal clear.
"You are part of the (asylum seeker) legacy caseload, if you wish to apply for protection, you now have a date in which you must do that, and if you do not do that, there will be consequences," she said.
"This is far less a dog whistle than it is a fog horn," Senator McKim fired back.
Mr Pezzullo said following Mr Dutton's announcement, his department would consider how to "aggressively pursue a departure strategy" for those who do not comply.
It has also emerged the department is taking the best part of a year to process asylum claims and the wait time is only getting worse.
The average time taken is between 261 and 312 days, which is up from between 247 and 308 days in February, the hearing was told.
Senator McKim again quizzed immigration officials about why they were imposing the "unreasonably tight" deadline when processing times were growing.
Mr Pezzullo said the government was concerned some of the cohort had been living in the community for several years without a deep analysis of their backgrounds.
"We want to start engaging from an identity, biometrics, national security and other points of view with all the applicants as soon as possible," Mr Pezzullo said.
"We can start working on their identity and on their reasons for their coming to Australia, in some cases, over five years ago."
The so-called "legacy caseload" refers to roughly 30,500 asylum seekers who arrived by sea between late 2012 and early 2014, roughly 23,000 of whom have already formally applied for protection.
At the end of April, there were 7853 people who had not yet applied, which dropped to 7194 by May 14.
The department is aware of media reports legal service providers have waiting lists 3000 to 4000 places deep to help with such applications and fear they cannot clear this backlog by October.
But Mr Pezzullo is confident the lodgement strike rate is on track.