The insurance inside an IUL, which means indexed universal life, is priced like annual renewable term. That means its cost resets every year as you age. So do you have to reapply every few years? No. A viewer asked me that on a livestream, and the clip on requalifying for annual renewable term covers why your health rating stays put.
When you apply, underwriting assigns you a health rating, called a rate class, based on your health and history. That rating stays with the policy. Each year the cost of insurance goes up based on your age and the carrier's rates for your rate class, and your health doesn't enter into it again. If you get sick five years in, the carrier can't re-rate you or cancel the policy. As long as the premium you pay, or the cash value, covers the monthly charges, the coverage stays in force. Many whole life policies built for high cash value carry a term rider priced the same way, and it works the same.
What can change is the carrier's rate table. A carrier can raise its current cost of insurance rates, but only for a whole class of policies, and only up to the guaranteed maximums in the contract. It can't single out one policyholder because their health changed. What an IUL carrier can change after you buy lists what's locked and what isn't.
The rising cost is why I design IULs to be funded well above the minimum. The cash value has to grow faster than the insurance charges, and in a policy funded close to its limit, those charges stay small for decades. In the designs I build, the cost of insurance doesn't really start to climb until your 70s.
Underwriting does come back in one situation, and it's when you ask for more coverage. Raise the death benefit, or try to put in more premium than the policy was designed to take, and the carrier can require new underwriting. Part of the reason is protecting itself from someone in a hospital bed trying to buy as much insurance as they can. Lowering the death benefit needs no approval, since it reduces what the carrier owes. It can still cause a problem, though. A lower death benefit can turn a well-funded policy into a modified endowment contract, or MEC, which loses the tax-free treatment of policy loans, and I covered that in cutting the death benefit can turn a healthy policy into a MEC.
Your health can also work in your favor: if you were rated for a condition that has since improved, you can ask the carrier to reconsider your rating, as described in getting a table rating removed after your health improves.
Planning to put more into a policy than it was designed to take? Ask the carrier whether that needs new underwriting before the money goes in, while your health is still what it was when you applied.