What Is Field of Membership?
Field of membership (FOM) is the legal definition of who is eligible to join a credit union. Federal law (the Federal Credit Union Act) and NCUA regulations require every federal credit union to have a defined FOM. State-chartered credit unions are subject to their state's equivalent requirements. The FOM is not arbitrary — it reflects the historical "common bond" principle that credit unions exist to serve a specific community of mutual interest.
Types of Field of Membership
1. Community Charter
The most common type for modern credit unions. A community charter allows membership for anyone who lives, works, worships, or attends school in a defined geographic area — typically a county, city, Metropolitan Statistical Area (MSA), or rural district. Community credit unions are open to the general public within their area, similar to a local bank. Anyone in the community can join, regardless of employer or organizational affiliation.
2. Single Common Bond (Occupational)
Membership is limited to employees of a specific employer or group of employers (e.g., "employees of Boeing" or "employees of the State of Texas"). These credit unions originated as workplace cooperatives, often in the early and mid-20th century.
3. Multiple Common Bond
Membership extends to employees of multiple employers, often in a related industry or geographic cluster. For example, a credit union may serve employees of 50 small businesses in a downtown commercial district.
4. Associational
Membership is tied to belonging to a specific organization — a trade union, alumni association, church, ethnic organization, or professional group. Some of these organizations have very broad membership themselves, which in turn makes the credit union broadly accessible.
How to Determine Your Eligibility
The best way to confirm eligibility is to review the credit union's website (under "Membership" or "Join") or call the credit union directly. When searching on this site, each credit union's membership type is listed on its profile page. The NCUA also maintains charter information at ncua.gov.
Credit Unions Anyone Can Join
Some credit unions have community charters broad enough to admit virtually any US resident, or offer a "back door" to membership through a qualifying organization (e.g., you can join by making a small donation to a specific nonprofit). Examples include Alliant Credit Union (former United Airlines employees' CU) and Pentagon Federal Credit Union (PenFed), which extended membership to any US citizen or resident through a $5 donation to a qualifying organization.
What Happens If You Move?
Once a member, always a member — as long as you maintain the minimum balance in your share savings account. You do not lose membership if you move out of the community area, change employers, or leave the qualifying association.
Frequently Asked Questions
Usually yes. Most credit unions extend membership eligibility to immediate family members of existing members — typically spouses, children, parents, and siblings. Many also extend to members of the same household. Check the specific credit union's policy.
A SEG is an employer or organization that has a formal relationship with a credit union, allowing that employer's employees to join the credit union. Smaller credit unions often expand their membership by adding SEGs from local businesses.
Yes. Once you are a member of a credit union, you retain membership as long as you maintain the minimum balance — even if you no longer work for the qualifying employer.
A few credit unions have very broad eligibility. PenFed and Alliant Credit Union are well-known examples that have extended open membership to most US residents. The NCUA's credit union locator can help you find others in your area.
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