The best IUL for retirement will vary from person to person. However, to make it ideal for retirement, it is encouraged to join an IUL policy early and accumulate cash value over decades. This way, the individual will have enough cash value to use for retirement-related expenses.The best IUL for retirement will vary from person to person. However, to make it ideal for retirement, it is encouraged to join an IUL policy early and accumulate cash value over decades. This way, the individual will have enough cash value to use for retirement-related expenses.