Life insurance is priced on age. Every contract carries a provision covering what happens when the age on the application turns out to be wrong. It's called misstatement of age, and the answer isn't the one people fear. The carrier doesn't void the policy and doesn't deny the claim. They resize the death benefit to whatever the premium you actually paid would have bought at your real age.
Say you're 47 and the application said 45. You paid a 45-year-old's premium every year, and a 45-year-old's dollar buys more coverage than a 47-year-old's dollar. So the carrier reduces the death benefit to the amount that premium would have purchased at 47. On a $500,000 policy that might come back as $470,000, depending on the product and how far off the age was. The family still gets a check. It's just a smaller check than the number on the front page of the contract.
It runs the other direction too. If the application overstated your age, you overpaid, and the death benefit gets adjusted upward.
Most contracts include sex in the same provision, since rates differ by sex on most products. Same treatment, same arithmetic.
The age provision is separate from the contestability period, which is the first two years, when a carrier can investigate and rescind the contract over a material misrepresentation. The two-year window inside every new policy covers that one. Age is carved out of it. A wrong birth date gets adjusted at any time, thirty years in, on a claim, with no time limit at all.
Why it surfaces decades after an application nobody remembers is that the carrier verifies age at claim time. The beneficiary submits a certified death certificate, and the birth date on that certificate is the one the carrier uses. A typo in a policy number gets caught in a week. A birth year typed as 1978 instead of 1976 sits there for thirty years and nobody looks at it.
Where it actually bites is on a policy funded to build cash value, because the age error runs through everything downstream. Cost of insurance charges in an IUL, which means indexed universal life, are age-based and get recalculated. The maximum premium the tax code allows is age-based too, so a corrected age can move the MEC limit, and MEC means modified endowment contract, the classification that turns loans and withdrawals into taxable events. A policy that sat safely under that line at the stated age might not sit under it at the real one. The MEC line explains what that limit does. Correcting an age on a heavily funded contract is a call to the carrier, not a guess.
Check it now instead of leaving it for your beneficiary. Pull the policy and look at the data page, where the insured's name, date of birth, issue age, and rate class are printed together. Compare that birth date against a driver's license or a birth certificate. If it's wrong, call the carrier's policyholder service line, tell them you've found a date-of-birth discrepancy, and ask what documentation they need to correct it. A correction made while you're alive is paperwork. A correction made at claim time is a smaller check to your family.