What balance does the bank use to authorize my ATM and everyday debit card transactions on business accounts?

We use your available balance to determine whether to authorize transactions for payment. If you have a line of credit linked to your account for overdraft protection, we add the amount of funds available under the line of credit to your available balance. If we authorize the transaction, we then place an Authorization Hold on your account in the amount of the authorization request which immediately reduces your available balance by the amount of the request.

For example, assume that on Monday you have a ledger balance of $50 and an available balance of $50. If you were to use your debit card at a merchant on Tuesday to buy supplies for $20, then that merchant could ask us to immediately authorize the payment. If we do so, then we will reduce your available balance by the amount authorized, which is $20. Your ledger balance would still be $50 because this transaction has not yet posted to your account, but your available balance would be $30 because you have a pending commitment to pay the merchant $20. When the merchant presents the transaction for payment, your ledger balance will be reduced by the amount of the posted transaction (in this example, $20) and both your ledger balance and available balance will be $30 (assuming no other intervening transactions occurred).