When you authorize a refund through direct checkout, Etsy will pull the money from your payment account. If there isn't enough funds in there to cover the refund amount that you have authorized then Etsy will charge your bank account for the excess refund amount. This has happened to me a few times when I had to issue a refund that processed on the same day that Etsy deposited my payment account into my checking account. That was the only time it's ever happened that way. I think I just messed up on the timing and had to reconcile that 'expense' in my accounting software.