Standard Form 2808 at a glance
What it is: Designation of Beneficiary under the Civil Service Retirement System is used to designate who is to receive a lump-sum payment which may become payable after your death.
Where and when to file: Your designation is not effective until OPM receives and certifies it. Mail both copies of your designation of beneficiary to: U.S. Office of Personnel Management Retirement Operations Center P.O. Box 45 Boyers, PA 16017-0045. To be valid the designation must be received and certified by the Office of Personnel Management before your death.
Use this form ONLY if you are or were covered by the Civil Service Retirement System. If any portion of your service was under the Federal Employees' Retirement System, use Standard Form (SF) 3102.
A filled-in Standard Form 2808 example: an employee names two beneficiaries

How to fill out Standard Form 2808, box by box
A. Identification

Enter your Name (last, first, middle), Date of birth (mm/dd/yyyy) and Social Security Number.
Place an "X" in the block that applies to you: An employee, Retired or an applicant for retirement, or Former employee eligible for retirement in the future.
If you are retired, give your claim number.
Enter the Department or agency in which presently employed (or former department or agency), with the Bureau, Division and Location (city, state and ZIP code).
B. Information Concerning The Beneficiaries

For each beneficiary, enter the First name, middle initial, and last name, the Address (including ZIP code), the Relationship to you and the Share to be paid to each beneficiary.
If you designate more than one beneficiary, be sure that the shares to be paid add up to 100 percent. Do not use dollar amounts to indicate the shares.
If you want to designate your estate as beneficiary, enter "My estate" as the name of the beneficiary.
You can designate any person, firm, corporation, or legal entity as your beneficiary.
If more than one beneficiary is named, unless otherwise indicated, the share of any beneficiary who may predecease you or who may be disqualified for any other reason is distributed equally among the stated beneficiaries or entirely to the survivor. If none of the beneficiaries are alive and eligible to receive payment when a lump sum becomes payable, this designation is void and payment will be made according to the order of precedence set by law.
Name the beneficiary or beneficiaries to receive any lump-sum benefit which may become payable under the Civil Service Retirement System (CSRS) after your death. This designation of beneficiary will not affect the rights of any survivors who may qualify for annuity benefits after your death, cancels any previous designation of beneficiary, and remains in effect until you cancel it in writing.
OPM will write to the address of each beneficiary that you provide in Part B to contact the person you designate. However, that person is obligated to get in touch with OPM after your death to ask OPM to make payment.
Date of designation and Your signature
C. Witnesses

The undersigned witnesses certify that the person identified in A. Identification signed in their presence.
Each witness signs on the Signature of witness line and enters the Address (including ZIP code).
A designation of beneficiary must be in writing, signed, and witnessed.
A witness to a designation of beneficiary is not eligible to receive payment as a beneficiary. You do not need to make a designation if you are satisfied with the order of precedence the law provides and you do not have a certified designation on file.
More rules for Standard Form 2808
Standard Form 2808 Revised June 2011. The December 2008 revision is usable.
If your situation is different
You wish to designate more than four persons or to change a beneficiary
If you wish to designate more than four persons in Part B, use a blank sheet of paper which you will attach to the form.
Print your name and date of birth at the top of the attachment and provide the information required in Part B for each beneficiary.
Your signatures on the form and on the attachment must be witnessed by the same two people. The witnesses must sign both the form and the attachment. You can change your beneficiary at any time, without the knowledge or consent of a previous beneficiary, and this right cannot be waived or restricted.
The name or address of a beneficiary changes
To inform OPM if the name or address of a beneficiary changes, file a new designation of beneficiary.
OPM will pay the person you designate, even if that person's name or relationship to you changes after you file this designation. For example, suppose you designate your spouse and then you two divorce and you marry someone else. OPM will pay any lump sum to your former spouse unless you submit another designation to cancel prior designations or to designate who OPM is to pay.
A designation of beneficiary remains in effect until (1) you cancel it by filing a new designation or (2) you receive a refund of your retirement deductions before retirement.
Before you go
The filing of this form will completely cancel any Designation of Beneficiary under the Civil Service Retirement System you may have previously filed. Be sure to name in this form all persons you wish to designate as beneficiaries of any lump sum payable at your death.
Common questions about Standard Form 2808
When is this form not the right one?
Do not confuse this form with designation forms used for other types of benefits: SF 2823, Designation of Beneficiary, Federal Employees' Group Life Insurance Program; SF 3102, Designation of Beneficiary, Federal Employees' Retirement System; TSP-3, Federal Retirement Thrift Savings Plan Designation of Beneficiary; or SF 1152, Designation of Beneficiary, Unpaid Compensation of Deceased Civilian Employee.
Sources
[1] Standard Form 2808 (Revised June 2011), Designation of Beneficiary, Civil Service Retirement System, U.S. Office of Personnel Management (the Official source link on this page).


