The IRS explains, in simple terms, the purpose of a conflict of interest policy:

Charitable organizations are frequently subject to intense public scrutiny, especially where they appear to have inappropriately benefited their officers, directors, or trustees. The IRS also has an oversight role with respect to charitable organizations. An important part of this oversight is providing organizations with strategies that will help avoid the appearance or actuality of private benefit to individuals who are in a position of substantial authority. The recommended conflict of interest policy is a strategy we encourage organizations to adopt as a means to establish procedures that will offer protection against charges of impropriety involving officers, directors, or trustees.

A conflict of interest occurs where individuals’ obligation to further the organization’s charitable purposes is at odds with their own financial interests. For example, a conflict of interest would occur where an officer, director, or trustee votes on a contract between the organization and a business that is owned by the officer, director or trustee. Conflicts of interest frequently arise when setting compensation or benefits for officers, directors, or trustees. A conflict of interest policy is intended to help ensure that when actual or potential conflicts of interest arise, the organization has a process in place under which the affected individual will advise the governing body about all the relevant facts concerning the situation. A conflict of interest policy is also intended to establish procedures under which individuals who have a conflict of interest will be excused from voting on such matters.

Apart from any appearance of impropriety, organizations will lose their tax-exempt status unless they operate in a manner consistent with their charitable purposes. Serving private interests more than insubstantially is inconsistent with accomplishing charitable purposes. For example, paying an individual who is in a position of substantial authority excessive compensation serves a private interest. Providing facilities, goods, or services to an individual who is in a position of substantial authority also serves a private interest unless the benefits are part of a reasonable compensation arrangement or they are available to the public on equal terms and conditions.

• Here is a sample Conflict of Interest Policy
• Here is a sample board of directors’ resolution to adopt the new policy