Authorization. (1) Upon receipt of satisfactory evidence of the facts by the district director or director of the service center, he may make allowance for or redeem stamps issued under the authority of any internal revenue law if—

The stamps have been spoiled, destroyed, or rendered useless or unfit for the purpose intended, or

The owner of the stamps has no use therefor.

If a stamp has been in use for any period of time, it may not be redeemed under section 6805. Similarly, no allowance shall be made for stamps which have been lost or stolen.

Method and conditions of allowance. Such allowance or redemption may be made, either by giving other stamps in lieu of the stamps so allowed for or redeemed, or by refunding the amount or value to the owner thereof, deducting therefrom, in case of repayment, the percentage, if any, allowed to the purchaser thereof. Claims for the redemption of or allowance for stamps shall be made on Form 843 and filed with the district director or director of the service center within three years from the date of the purchase of the stamps from the Government. The stamps for which redemption or allowance is claimed shall be submitted with the claim. If the stamps are destroyed or damaged to the extent that they cannot be presented for redemption or allowance, proof satisfactory to the district director or director of the service center that they have been destroyed or so damaged must accompany the claim before allowance or redemption shall be made. In any case where the actual date of purchase of the stamps from the Government cannot be established, it must be definitely shown in the claim whether they were so purchased within three years prior to the date of filing of the claim.

Time for filing claims. No claim for the redemption of, or allowance for, stamps shall be allowed under this section unless presented within 3 years after the purchase of such stamps from the Government.

Finality of decisions. The findings of fact in and the decision of the district director or director of the service center upon the merits of any claim presented under or authorized by this section, shall in the absence of fraud or mistake in mathematical calculation, be final and not subject to revision by any accounting officer.