I just checked my HSA account after using my debit card for a bi-annual dental cleaning, and the numbers weren't adding up for my expected balance. The debit card transaction is still pending, but the PreAuthorization is still on the card as well (it currently looks like a double transaction, which makes my balance $141 lower than it should be). I expect that this will disappear eventually, but it makes me wonder if I need to be cautious about using my card even when I have enough to cover the expense (i.e., if I have a $1,200 transaction when I only have a $1,400 balance).
Is this normal practice? What would happen if I didn't have double the balance of this transaction available in my account?