Waiver of premium is a rider that makes the carrier pay your premium if you become disabled and can't work. The policy stays in force, the cash value keeps building, and the death benefit stays intact, all without a dollar from you.
How the contract defines disability decides everything. Some contracts use own-occupation, meaning you qualify if you can't perform your own job. Others use any-occupation. That means you have to be unable to do any work you're suited for, and it's a much harder bar to clear. Read which one you have before you assume the rider will fire.
There's a waiting period, usually six months, and you keep paying during it. If the claim is approved, most carriers refund the premiums paid during that window. There's also an age limit on when the waiver stops, often 60 or 65.
On a high cash value design, the question is what the rider waives. Some carriers waive only the base premium and leave the paid-up additions rider unfunded. Others waive the full scheduled premium including the PUA. That gap decides whether the policy keeps compounding through a disability, or just survives and stops growing.
Underwriting for the rider is separate. A carrier will issue the policy and turn down the waiver. Or issue it with one condition carved out. Either way that shows up in the policy pages, not in the illustration. Read the rider page when the contract arrives, not just the ledger.
It costs something, usually a small percentage of premium, and that cost comes out of dollars that would otherwise buy cash value. On a policy built for accumulation, every charge competes with the growth engine. The trade-off is that a disability is exactly the event that ends a funding plan, so the rider protects the thing the plan depends on.
If you already carry good individual disability insurance, check whether that benefit alone is big enough to cover the premium. Plenty of households are paying for the same protection twice.