What is the best practice to protect the financial institution from loss when opening accounts for businesses in regards to identifying corporate officers or other representatives acting on behalf of the business? How far should we take this?

The corporate documents (Articles of Incorporation) will tell you who is able to open accounts on behalf of the corporation and further, what powers they have in regards to these accounts. You need to see them. Then, proper ID for owners would be the standard ID forms you would take for any other account you open.

Is it common practice to validate that the person opening the business account or wishing to sign on the account is actually the "secretary" or other officer of the corporation?

From a common-sense fraud prevention perspective, it should be SOP to verify that (1) the person signing the affidavit of corporate resolutions is the corporate secretary/clerk or other officer, (2) the persons named as officers on the resolution are, in fact, holders of those offices, and (3) the persons signing the signature card are, in fact, who they say they are.

After all, Banking 101 requires that the bank satisfy itself as to the persons' (1) identity and (2) authority.

In an earlier post, you mentioned using the Annual Filing as a means to identify this person. I suppose this is really the only way to do such. Our state's website provides little info about the officers of a corporation.

All good advice, but I'd add "don't lose sight of the obvious". Do you know the business and its office/ premises? If you don't know the business check it out to see if the business's real address matches the account opening info, using a business directory, yellow book, etc.

If the address given when the account is opened doesn't match you may have the address for a legitimate "branch office", but you may not!

The annual filing may not tell you much about the officers, but if you combine that with the corporate documents (original corporate bylaws) you'll see both the current people authroized to act on behalf of the corporation and the limitations of those acts (based on the bylaws and articles of incorporation). Being President of the Corporation may not necessarily mean I can open a checking account on my own. It may be that I need the secretary, or perhaps two corporate officers, or myself and blah blah, the list goes on. The bylaws and articles of incorporation cover this for you.

Absent this information, how on earth do you open an account for a corporation and verify the people signing your documents are actually entitled to do so?

Some states allow you to check principals of a corporation on the secretary of state's website. Also, if it is not a new business, ask them where they were banking and why they left.

These opinions are mine and not those of my employer.