You can use your HSA funds to pay for eligible expenses incurred any time after you open your HSA. There is no time limit between when you incur the qualified expenses and when you withdraw the corresponding amount from your HSA. You may also elect to pay for current qualified medical expenses out-of-pocket, so that you may invest your HSA funds and grow the account for future use. It is recommended that you always save your itemized receipts and other paperwork to verify eligible expense for when you do withdraw funds, whether it is now or in the future.