For the purposes of this subpart, the claimant, or owner, shall be treated as having borne the ultimate burden of an amount of tax only if:

(a) He has not, directly or indirectly, been relieved of such burden or shifted such burden to any other person,

(b) No understanding or agreement exists for any such relief or shifting, and

(c) If he has neither sold nor contracted to sell the articles involved in such claim, he agrees that there will be no such relief or shifting, and furnishes bond as provided in § 46.10.