This would depend on the type of travel insurance and the benefits that you need. Many policies have an advantage period where you receive cover for benefits that will not be covered if purchased outside the advantage period (usually 10 – 21 days from first deposit). The benefits affected are typically pre-existing conditions, financial default and terrorism. Most policies which offer “cancel for any reason” or “cancel for work reasons” also require purchase within the advantage period. it is also important to remember that the earlier you purchase the insurance, the sooner you are protected against an unforeseen event. Once an event has occurred, it is too late to purchase insurance and be covered for that reason.