Publication 969 - Generally, distributions from a health FSA must be paid only to reimburse you for qualified medical expenses you incurred during the period of coverage.
You won't be able to use the 2018 FSA funds to pay off your 2017 medical expenses, but you may be able to deduct your 2017 medical expenses if you itemize your deductions and the medical expenses exceed 10% of your Adjusted Gross Income (7.5% if you are 65 and older).
