My wife had several doctors appointments between August of 2018 and May of 2019. As it turned out, we pre-paid for appointments that insurance ended up paying for in full. The doctor used the credit for other appointments but eventually we no longer needed to see them before the credit was used up. So, we had an overpayment of about $270 on my wife's account, although I didn't know it at the time.
We had already paid and I had receipts so I immediately reimbursed ourselves from our HSA. I only know about the overpayment now because I requested an itemized statement from the doctor's office.
Most advice says to re-deposit the money into the HSA as a mistaken distribution. But, several places (like this Intuit forums question) state that I can simply use the money towards future HSA reimbursements for that same year. For example, later in 2019 we had a $1,000 reimbursable expense. Could I subtract this $270 from the $1,000 reimbursement (therefore only reimbursing $730) and then "call it even"? Would this be allowed by the IRS?
This would be helpful since I no longer have an account with the HSA that I took the distribution from. I'm not sure if my new custodian will accept the deposit for a mistaken distribution from a different HSA. If not, how can I handle that?