One of the first things the owner of a new business has to do is establish a relationship with a bank. The bank, probably a commercial bank, should be one with capabilities that match the needs — actual and potential — of the new company. Each state has its own regulations for opening business bank accounts. Documentation requirements are the same for unincorporated associations and companies. A call to the bank should tell you exactly what documentation you'll need to open a business bank account.

Taxpayer Identification

Your first step in applying for a business bank account is to present the taxpayer identification number for your business. This is called the employer identification number for companies and is obtained through the Internal Revenue Service. If your business is a sole proprietorship, your Social Security number will suffice.

Proof of Business Identity

You will have to show the bank that your business has been formed properly according to state law. For corporations, show the articles of incorporation or certificate of incorporation. Nonprofit corporations must provide an Internal Revenue Service ruling letter of tax exemption under Section 501(c) of the Internal Revenue Code. Articles of organization are needed for limited liability companies. If you are applying on behalf of a limited partnership, present your limited liability partnership agreement, showing the business name and the names of the partners, or the certificate of limited liability partnership, also showing the name of the business and the names of the partners. For unincorporated associations, bring the articles of association or bylaws. Proprietorships should provide a business name filing document or a business license showing the names of the business and the owner.

Corporate Authorization

Banks also require proof that the business has approved the opening of an account. Corporate resolutions to this effect must identify the authorized signers on the bank account.

Bank Application Form and Signature Cards

Banks will require that their own application form be filled out at the time of the account opening. The completed form will contain all contact information for the account party: mailing address, telephone numbers and the names of company officers and key personnel. Signature cards will bear the typed names and original signatures of those who will be signing checks and any other account documentation. Fresh cards will have to be completed when new signers assume their duties.