If you already own a life insurance policy, and the policy was issued to you as a nonsmoker, if you start smoking it will not increase your prices. You do not need to worry about this affecting your life insurance policy in any way. The life insurance company can not contest a claim, and they can not void your policy. Once a policy is issued, it is not affected by a change in the habits or health of the insured person. You can relax, your beneficiaries do not need to worry about the insurance company denying a payout because you picked up a smoking habit.
Life insurance companies know that a certain percentage of people who are nonsmokers will start smoking one day. While it may not be a very large percentage of the population who does this, it will happen. Just like life insurance companies know that people who have normal blood pressure may one day develop high blood pressure, or have a heart attack or stroke, it is factored into the statistics when the policy is sold.
Marijuana and Vaping
Just like with tobacco smoke, marijuana and vaping are generally viewed as “smoking” for the purposes of life insurance health ratings. Some companies are beginning to handle these habits 
differently from tobacco smokers, but most will assign a smoker rating.
If you start smoking marijuana or if you start vaping nicotine after you are issued a life insurance policy, you do not need to worry about it affecting your rates or policy standing. Your rates are locked in at issue so the insurance company does not have the right to increase them except for specified by the contract (such as renewal at the end of the term duration). The insurance company can also not cancel your policy or deny a claim to your beneficiaries for picking up a habit after the policy was issued.
What if you Lied
If you lied about being a smoker and the life insurance company didn’t detect nicotine in your blood during the health exam (maybe you stopped briefly), there may be some complications when it is time to pay a claim. While they technically have an argument that they don’t need to pay a claim, in reality, they still will. It will cause a lot of heartburn for your beneficiaries though and delay your claim. It also opens the door for the insurance company to deny the claim. What the standard process for most companies is, is re-underwriting the policy with the knowledge that you were a smoker. If they still would have issued the policy according to their published underwriting guidelines, they will pay the claim (minus the difference in higher premiums that would have been owed with a smoker rate).
If a life insurance company finds out about this while you are still alive, it is technically fraud. This is not something that you are going to be charged with or prosecuted for, but the insurance company probably has the right to terminate your policy. If you are lucky they may even want to keep your business and not terminate the policy. They will require you to pay them smoker rates going forward, though. If you are a smoker it is best that you tell the truth, and search for the lowest priced smoker policy that you can find.
What About Quitting
If the reverse is true, and you have been issued a policy and then later stopped smoking, your rates can actually go down. Most life insurance companies require you to be tobacco and nicotine free for a minimum of 2 years. You can apply for what is known as reconsideration. If it is accepted, the smoker rating is removed from the policy. While better than paying smoker rates, this still leads to a higher amount of premium being paid in most cases, than if the policy was issued as a nonsmoker policy to begin with. This is because the highest smoker rating is still a “standard” rating, so when the smoker rating is removed the policy is still standard. This is quite a bit more expensive than a premier or preferred rating.
