hildhood vaccination coverage in Australia is high by international standards. 1 Coverage increased from 1997 with the introduction of vaccination incentives and improved recording in the Australian Childhood Immunisation Register (ACIR), 2 especially among 12-and 24-month-old children, but plateaued at 90-92% in the decade to 2014. 2,3 The proportion of 12-month-old children deemed fully vaccinated reached 93.9% in 2018, and that of 60-month-old children reached 94.0%, having increased from less than 83% in 2009. 4 These figures are close to the national target of 95%, the level required for herd immunity for measles control. 5 A number of initiatives for increasing vaccination coverage in children have been introduced in Australia in recent years. State-specific "No jab, no play" policies, adopted by four of eight jurisdictions by January 2020, permit children to attend childcare only if they are fully vaccinated, enrolled in an approved catch-up program, or have medical reasons for not being vaccinated. 5 The national "No jab, no pay" policy, 6,7 introduced on 1 January 2016, extended the existing vaccination requirements for receiving federal family assistance payments 8 by removing nonmedical (conscientious objection) exemptions and tightening guidelines for medical exemptions. 5,9 Payments with vaccination requirements-the Family Tax Benefit part A supplement and Child Care Benefit/Child Care Rebate (replaced by the Child Care Subsidy from July 2018)-may total $15 000 per child per year for lower income families. 7 In 2016-17, 39% of the more than 4 million families in Australia with children received the means-tested Family Tax Benefit part A, and 22% received the Child Care Rebate (not means-tested at that time) or the Child Care Benefit. 10-12 Until 2012, vaccination requirements for family assistance payments were assessed at 2 and 5 years of age, and at 1, 2, and 5 years of age during 2012-2015. 8,13,14 Under "No jab, no pay", they were initially assessed annually to the age of 20 years, but eligibility for the Child Care Subsidy has been assessed fortnightly since 1 July 2018. "No jab, no pay" was accompanied by ACIR extending its recording of vaccinations to 20 (instead of 7) years of age, and subsequently expanding to the whole-of-life Australian Immunisation Register (AIR) as part of a package of initiatives for strengthening the vaccination program. 3 Some countries have long standing compulsory vaccination policies, and others have recently introduced or are considering them, but national monetary sanction policies are unique to Australia, 15 attracting international interest. 9 Evidence for their effectiveness in increasing vaccination rates is limited. 8,15 Given its greater impact on socioeconomically disadvantaged families, the effectiveness of "No jab, no pay", its impact on access to early childhood education, and other aspects of social equity have also caused concern. 6,7 The effects of "No jab, no pay" have not been formally assessed. As vaccination coverage increased both before and aft...