Tax deduction on health insurance plans is available under Section 80D of the Income Tax Act, 1961. The maximum limit of deduction does not depend on the sum insured. As per Section 80D, the maximum limit of deduction is INR 25,000 which increases to INR 50,000 if you are aged 60 years and above. So, for your policy of INR 50 lakhs, premiums up to INR 25,000 would be allowed as a deduction. The remaining premium would be subject to taxation at your income tax slab rates.