If the age of the insured under a National Service life insurance policy has been understated, the amount of the insurance payable under the policy shall be such exact amount as the premium paid would have purchased at the correct age; if overstated, the excess of premiums paid shall be refunded without interest. Guaranteed surrender and loan values will be modified accordingly. The age of the insured will be admitted by the Department of Veterans Affairs at any time upon satisfactory proof.
38 C.F.R. §8.21