Section 2 (6C) of Insurance Act, 1938 defines Health Insurance Business as under:
"health insurance business" means the effecting of contracts which provide for sickness benefits or medical, surgical or hospital expense benefits, whether in-patient or out-patient travel cover and personal accident cover.

Health Insurance policies are offered by all Life, General and Health Insurance companies that are registered with IRDAI. While General and Heath Insurance Companies offer both indemnity based and benefit based health insurance policies, Life Insurance Companies offer benefit based policies as per the extant Health Insurance Regulations. All General and Health Insurance Companies also offer Personal Accident Policies, Domestic Travel Policies and Overseas Travel Policies. The names of the Insurance companies that are registered with IRDAI are available in IRDAI website www.irdai.gov.in.

In accordance to the provisions of Regulation 12(i) of IRDAI (Health Insurance) Regulations 2016 (HIR 2016), all health insurance policies shall ordinarily provide for an entry age of at least up to 65 years. There are also Health Insurance Products that offer Health Insurance Coverage beyond age 65 years. In accordance to the provisions of Regulation 12(ii) of HIR 2016,once a proposal is accepted in respect of a health insurance policy (except Personal Accident and Travel Policies) and a policy is issued which is thereafter renewed periodically without any break, further renewal shall not be denied on the grounds of age of the Insured. Thus, health insurance policies are lifelong renewable.

As part of Guidelines on Standardization, IRDAI has defined Pre-Existing Diseases (reproduced below in verbatim), at Clause 33 of Chapter I of Guidelines on Standardization in Health Insurance under Sec 1 of IRDAI Master Circular ref IRDAI/HLT/REG/CIR/193/07/2020 dated 22.07.2020:
Pre-existing Disease means any condition, ailment, injury or disease:
a) That is/are diagnosed by a physician within 48 months prior to the effective date of the policy issued by the insurer or its reinstatement or 
b) For which medical advice or treatment was recommended by, or received from, a physician within 48 months prior to the effective date of the policy issued by the insurer or its reinstatement.
(Life Insurers may define norms for applicability of PED at Reinstatement)

Offering health insurance coverage to any person who has suffered / suffering from any disease / illness is subject to underwriting policy and product design of an insurer. Insurers design products keeping in view certain factors such as viability and self-sustainability of products and the needs of the intended target market segment. Where a pre-existing disease(s) is disclosed and a health insurance policy is granted, such pre-existing disease(s) shall be covered after a waiting period as specified in the policy, which at the maximum shall not be exceeding 48 months.

However, in terms of Chapter IV of the Guidelines on Standardization of Exclusions in Health Insurance Contracts under Sec 1 of IRDAI Master Circular ref IRDAI/HLT/REG/CIR/193/07/2020 dated 22.07.2020, certain existing diseases disclosed by the prospect are allowed to be permanently excluded.