Here is a $5,000 mistake people make without knowing it.
You can only reimburse a medical expense that happened on or after the date your HSA was established. Open the account in March, and every bill from January and February is gone. Not delayed. Gone. You can never pull those dollars out tax-free.
This is the establishment rule, from IRS Notice 2004-50. It is the quiet trap under the whole "save your receipts forever" strategy.
What "established" means
Your HSA is established on the date the account is opened under your state's law. For most people that is the date the account is actually open and able to receive a contribution, not the date you became HSA-eligible.
Being on a qualifying high-deductible health plan is not enough. The account has to exist.
The trap, with numbers
Say you start an HDHP on January 1 but do not open the HSA until you get around to it in April.
Between January and April you have $5,000 in medical bills. None of it is reimbursable from the HSA, ever, because the account did not exist when those expenses were incurred.
You paid $5,000 with after-tax dollars and you can never get it back tax-free. That is the entire loss.
The fix takes ten minutes
Open and fund the HSA the day you become eligible. You do not need to max it. A single dollar establishes the account and starts your reimbursement clock.
So the move is: the moment your HDHP starts, open the HSA and put in at least $1. Now every future expense is on the table, and you can fund the rest whenever cash allows.
One nuance worth knowing
In most states an HSA is not established until it is both opened AND funded. An empty shell may not count. So do not just open the account. Fund it with something, even a token amount, to lock the date.
| Action | Establishes the account? |
|---|---|
| Becoming HDHP-eligible | No |
| Opening an empty HSA | Sometimes (state-dependent) |
| Opening and making a first contribution | Yes |
The cost of doing this right is one dollar and ten minutes. The cost of doing it wrong is every receipt you collect before the account exists.
*This is educational content, not financial or tax advice. Consult a qualified professional before making decisions about your HSA.*