All qualified expenses incurred AFTER the HSA is open/established are eligible for payment with tax-free dollars.
These expenses don’t have to be paid with HSA funds at the point of service. Instead, the account holder can pay for the expense with post-tax dollars (out of his/her regular bank account or with a credit card).
In this case, the account holder can hang on to the receipts and reimburse him or herself in the future. It doesn’t even have to be in the same year.
To avoid penalties, have a good filing system and just make sure that at any point the sum total of receipts for all eligible expenses is equal to or greater than the total of all payments and withdrawals from the Health Savings Account.