The receipt for his 8ft-high limestone tablet, engraved with six key policy pledges, was found by party officials after a frantic search at its headquarters when the elections watchdog said it had not been filed.
Some newspapers estimated at the time it could have cost up to £30,000.
A Labour spokesperson claimed Miliband's monolith was omitted from a document detailing election spending because of an "administrative error", saying that the issue would be dealt with "as soon as possible".
He had intended to reveal it in a school hall, but but the floor was not strong enough to support the two-tonne slab, forcing him to pose for pictures outside instead.
It was roundly mocked at the time, with Boris Johnson criticising it as "absolutely crazy" and "a waste of good stone".
Others, including one of the show's writers, compared it to a scene from political satire TV show 'The Thick Of It'.
But Miliband himself defended the move, saying it had at least "got people talking".
Fans of the Labour leader or election-memorabilia collectors will be disappointed to know that the stone was likely destroyed in the days after his defeat on May 7.