Orthodontia is an eligible flexible spending account (FSA) expense, but treatment and payment often occur over a number of years. FSAs are designed to reimburse expenses from services rendered during the coverage period, typically the corresponding 12-month benefit year.
Check with your employer to see whether they allow orthodontia to be reimbursed in advance of the services rendered or on a monthly basis based on a copy of the orthodontia contract. You should plan your FSA contributions based on the method of reimbursement allowed by your employer. FSA elections are irrevocable, meaning once you select your annual election amount, you cannot cancel or modify it.