In the US, it's possible to become overdrawn even if you wait for a check to clear. Assuming there is a check "writer" and a check "casher"
- A portion of the check is made available to the casher (said to be "cleared", but not really) before the writer's bank even responds
- After the writer's bank has cleared the check, it can still reverse the transaction and take back the funds. For example, if the check is found to be fraudulent.
So, for example, you can deposit a check into your account, wait a month to be sure it's cleared, take the money out, and then have the money "taken back"; leaving your account in the negative. As such, even for accounts that don't have any "line of credit", the bank still winds up "lending you money". Effectively, EVERY bank account in the US has credit built into it in some way.