What happens if an employer reimburses a claim from a FSA and it remains unsubstantiated? Should the employer file a 1099-MISC, or must it file an amended W-2?

Thanks for your help!!!!

What has me confused is that I would think the reimbursed expense becomes taxable income and that the employer would need to either off-set if during the same calendar year or otherwise file an amended return (1099 or W-2) if after the close of the calendar year. But if you look at Rev. Rul. 2003-43 regarding FSAs and debit cards, it suggests the employer need not ever treat it as "wages" and file and amended return. The Rev, Rul says the employer should just "treat the payment as it would any other business indebtedness." -- Hmmmmm