Most insurers have a list of pre-existing medical conditions that are automatically covered for free like asthma, cataracts, some types of diabetes, hypertension which do not require an assessment or declaration form to be submitted. If you have a pre-existing medical condition not listed, you may be able to get cover for an additional fee. Depending upon the seriousness and recency of the condition, your application may require further assessment. See more about pre-existing conditions and medical assessments here.