Although I imagine that Postmasters still get audited by the Treasury Department on a periodic basis, I'd bet they only hear from the Auditor if the books aren't quite in order. This card makes me wonder if there was a corresponding Official card which served just such a purpose.
This is a scarce example of early Official Postal Cards as used by the Government Departments. This one is Form 1292-2, printed by the GPO in May 1894 with an edition of 55,000 copies. The card is cancelled December 12, 1894.
Place mouse on image to see the reverse side of the card.