<prompt> Human: I am going to the doctor today and have an empty HSA. Am I able to go visit the doctor, put money in my HSA, and then reimburse myself after the visit? Or does the money have to be in there before the visit?  <response>: As long as your HSA has been established before you receive the service, yes. You can wait and reimburse yourself or pay from the HSA later, when the HSA has enough funds in it. There is in fact no deadline.Source: See also Publication 969 for IRS discussion of HSAs.Edit: I presume you will be paying out of pocket for this service now or whenever it gets billed in near future. And then reimbursing yourself later, having kept records, when the HSA balance is high enough. 