There's no formal certificate to apply for, since the government doesn't issue one. What landlords actually need is a current Healthy Homes assessment and an accurate compliance statement. To get an assessment, engage a qualified assessor or a provider experienced with the Healthy Homes Standards to inspect the property against all five requirements. The assessment findings then form the basis of the compliance statement included in the tenancy agreement. There's no central licensing body specifically for Healthy Homes assessors in the way there is for some other trades, so checking a provider's experience and asking what their assessment actually covers matters more than looking for a certificate that doesn't exist in any official form.