Yes, you can buy Overseas Travel Insurance even if you are traveling on an immigrant visa (e.g. H1-B Visa, Work permit, Green Card or Permanent Residency(PR)) . However, the maximum duration of your policy can only be 180 days. After 180 Days, You need to purchase the Policy from the country you are immigrating to. Some insurers provide cover to immigrants for 90 days and some others for 180 days. So select a plan according to your requirement.