IRS rules require your employer and flex benefits administrator to make sure that all funds spent out of the account are for eligible health care expenses. This is because the funds are pre-tax. If a debit card purchase cannot be automatically verified as an eligible health care expense, the flex administrator will contact you and ask that you show proof the transaction was for an eligible health care expense. This is called “substantiation.” Please respond timely to the request by providing an insurance EOB or other detailed receipt, otherwise, your debit card may be suspended and you may have to file paper claims. Any funds that you did not substantiate may be reported to your employer and included on your W-2 as taxable income.
Find more FSA-related FAQs here: https://www.optumbank.com/tennessee/customer-support/faqs/fsa-faqs.html.