In 2015, the Coalition introduced its own crackdown on the DSP. It forced new claimants to be assessed by a government-appointed doctor.
The national social security rights network found earlier this year that the policy was making life far more difficult for claimants.
The parliamentary budget office predicted that, if current trends continue, the government would save $4.8bn over the next decade, the report found.
The minister for social services, Dan Tehan, did not respond to requests for comment.