I am no longer a officer on a Nevada corporation but I''m still employed by it. I use my personal money, which I transfer back and forth fromy personal

As a general matter, a bank does not have the right to charge your account unless the charge is properly payable from your account. In the absence of a specific statement from the bank regarding why they deem themselves entitled to charge your account, we have to guess. A reasonable guess is that they treat the business account as your personal account and deem you to be personally liable for the overdraft. Since the bank as already helped itself to your money, the burden of proving that the bank has acted improperly may fall on you. The transfers in and out of the business account that you undertook in your personal capacity are problematic. Although you see them as "proof" of something, all they really prove is that you failed adequately to distinguish between your personal funds and the funds of the business. In other words, in terms of legal art, you treated the business account as an "incorporated pocketbook" and provide the bank with an excuse to pierce the corporate veil in order to hold you personally liable for the debts of the business. Banks will usually negotiate over these matters and will often settle them if they are threatened with litigation or sued. You should consult with an attorney regarding this claim.