Form SF 3106A at a glance
What it is: The Current/Former Spouse's Notification of Application for Refund of Retirement Deductions Under the Federal Employees Retirement System.
Who signs: The current or former spouse's signature must be witnessed in Part 3. You may not be a witness.
If you apply for a refund of retirement deductions, you must notify your current spouse. Also, you must notify any former spouse if the following conditions apply: (1) You have 18 months of creditable civilian service; and (2) You were married to the former spouse for at least 9 months.
Your retirement contributions may be refunded to you only if you notify any current spouse (including any person from whom you are legally separated) and any former spouse who is still living.
You are not required to notify a former spouse if you were not married to that person for a total of at least 9 months or you do not have a total of at least 18 months of creditable civilian service.
You should provide a copy of Standard Form 3106A, Current/Former Spouse's Notification of Application for Refund of Retirement Deductions (this form, front and back), to (1) your current spouse, if any, and (2) if you have at least 18 months of creditable civilian service, each former spouse that meets the criteria.
What to bring and attach to Form SF 3106A
Use a separate form for current spouse and each former spouse.
A filled-in Form SF 3106A example: an applicant fills in Part 1

How to fill out Form SF 3106A, box by box
Part 1 - To Be Completed By Applicant

To notify each current or former spouse of your application for a refund of your retirement deductions, complete Part 1 with your name, date of birth and Social Security Number and have the current or former spouse complete Part 2.
In Part 1, enter your Name (last, first, middle), your Date of birth (mm/dd/yyyy) and your Social Security Number.
Part 2 - To Be Completed by Current or Former Spouse

Complete Part 2 and have two witnesses complete Part 3 and then return the form to the applicant.
Payment of the refund of retirement deductions will end any entitlement you may have to a survivor annuity or portion of any annuity to which the applicant would otherwise have been entitled.
Complete Part 2 and have the witnesses complete Part 3 even if you are submitting a court order.
Sign Part 2 on the Signature (do not print) line: I have read the paragraph above and I understand that the above-named individual is applying for a refund of retirement deductions under the Federal Employees Retirement System.
In Part 2, enter the current or former spouse's Name (type or print legibly) and the Date signed (mm/dd/yyyy).
The current and/or former spouse(s) must sign the form and have the signature witnessed by two persons.
Part 3 - To Be Completed by Witnesses

The witnesses certify that Part 2 of this form was signed by the current or former spouse of the person named in Part 1 in their presence.
Each witness enters a Signature and a Date signed (mm/dd/yyyy).
Each witness enters a Name of witness (type or print legibly), an Address (number and street) and a City, state and ZIP code.
You cannot be one of the witnesses.
Information About Sending Court Orders to the Office of Personnel Management (OPM)

If you are legally separated or divorced from the applicant, you should know that a refund would end your potential entitlement to a survivor annuity and to any portion of any annuity to which the applicant would be entitled. If you have a court order that expressly relates to any portion of the applicant's retirement deductions, you should send a copy of the court order to OPM with a cover letter giving:
Payment of the refund will also end any eligibility you have to coverage under the Federal Employees Health Benefits Program.
The court order can be honored only if it is received before the refund is paid to the applicant. Send a copy of the court order and your cover letter to Office of Personnel Management, Federal Employees Retirement System, Attn: Refund, P.O. Box 45, Boyers, PA 16017-0045.
Cover letter giving: 1. The name, date of birth, and Social Security Number of the person applying for the refund; 2. Your statement that the court order has not been amended, superseded, or set aside; 3. Your name, date of birth, and mailing address.
If the court order states that any payments to you are subject to termination upon your remarriage, the cover letter giving a statement. The statement is that either (1) you have remarried and the date of the remarriage, or (2) that you have not remarried and that you will notify OPM within 15 days of a remarriage should you remarry in the future.
If the court order gives you a survivor annuity after the death of the applicant, also attach a copy of your birth certificate, if available.
A former spouse who remarries before reaching age 55 is not entitled to a survivor annuity. (Termination of the remarriage does not restore a former spouse's entitlement to a survivor annuity.) Remarriage does not affect a former spouse's court-ordered right to receive a portion of any annuity during the annuitant's lifetime, unless the court order provides otherwise. A former spouse may also lose entitlement according to the court order.
I believe I have a court order that meets the criteria described in the Information About Sending Court Orders. I am immediately submitting a copy of the court order and the required cover letter to the address provided in the Information About Sending Court Orders. Enter Today's Date (mm/dd/yyyy), the Date of court order (mm/dd/yyyy) and your Signature (do not print).
I have been unable to notify the following current or former spouse

The Office of Personnel Management (OPM) will attempt to notify (by certified mail return receipt requested) the current or former spouse at the address you give. If you decide you want OPM to make notification, it will cause a 6- to 8-week delay in the payment of your refund. OPM will not pay you the refund until OPM receives the signed return receipt.
In the box, write the name and current mailing address, including ZIP Code, of the current or former spouse you have been unable to notify.
More rules for Form SF 3106A
After Parts 2 and 3 have been completed, the form must be returned to you for attachment to your refund application.
Attach all signed and witnessed notification forms to your refund application.
Payment of your refund is subject to the terms of any court order (related to a divorce or legal separation) that expressly relates to any portion of your refund, if the payment of the refund would end the entitlement of a spouse or former spouse to a survivor annuity or a portion of your annuity. A court order cannot bar payment of a refund if you do not have a future annuity entitlement under the Federal Employees Retirement System.
If you do not know the current whereabouts of a spouse or former spouse, OPM may waive the requirement to notify that person. A waiver may be granted if you submit with your refund application:
1. A determination by a court or administrative agency empowered to make such determinations that the person is missing; or 2. Notarized statements from yourself and two other persons (one of whom is unrelated to you) stating that the person's whereabouts are unknown and detailing efforts to locate the person.
Sources
[1] Form SF 3106A (Revised September 2013), Current/Former Spouse's Notification of Application for Refund of Retirement Deductions Under the Federal Employees Retirement System, U.S. Office of Personnel Management (the Official source link on this page).
