OPM Tax Withholding Form: How to Change Federal and State Withholding on Your Annuity

Two Ways to Change Your OPM Withholding

OPM handles federal income tax withholding on your FERS or CSRS annuity. If you need to adjust it — because you're overwithholding, underwithholding, or your situation has changed — you have two options:

1. OPM Services Online at servicesonline.opm.gov — the fastest route; changes take effect according to OPM's processing schedule
2. Paper Form W-4P mailed to OPM — takes longer but works if you don't have a Services Online account

Both methods accomplish the same thing: telling OPM how much federal income tax to withhold from each monthly annuity payment. The W-4P form is an IRS form, not an OPM form, but OPM is the entity that processes it for federal retirees.

Changing Withholding Through Services Online

If you already have an OPM Services Online account:

1. Log in at servicesonline.opm.gov
2. Navigate to "Federal Tax Withholding" in the menu
3. Select your filing status (single, married filing jointly, head of household)
4. Enter any additional withholding amount you want deducted per month, or adjust the number of dependents and other income entries to calibrate your withholding
5. Submit the change

The system generates the equivalent of a W-4P based on your inputs. Changes take effect according to OPM's processing schedule.

If you don't have a Services Online account, you'll need your CSA claim number (from your annuity statement or benefit letter) to register. First-time registration includes identity verification that can take a few business days.

Using the Paper Form W-4P

Download Form W-4P from IRS.gov and complete it following the instructions. The redesigned W-4P (in effect since 2022) works similarly to the regular W-4 for wage earners:

• Step 1: Name, address, Social Security number, filing status
• Step 2: Complete the step if you have income from a job or more than one pension/annuity, or if you are married filing jointly and your spouse receives income from a job or pension/annuity. Use the Step 2(b) entries rather than a checkbox-only adjustment
• Step 3: Claim dependents if applicable
• Step 4: Additional adjustments — other income not from jobs or pension/annuity payments (which may include taxable Social Security), deductions above the standard deduction, and extra withholding per payment. TSP distributions follow their applicable TSP withholding rules

Mail the completed form to: OPM Retirement Operations Center P.O. Box 45 Boyers, PA 16017

Paper form changes can take longer than online changes. If timing matters (you're trying to fix underwithholding before year-end), use Services Online instead.

The Default Withholding Problem

When you first retire, OPM applies a default withholding status of single with no adjustments — regardless of your actual marital status. This default is intentional (it prevents underwithholding for retirees who don't submit a W-4P), but it can significantly misalign with your real tax situation in both directions:

Overwithholding scenario: A married retiree filing jointly with no other income might have too much withheld under the single default, resulting in a large refund at tax time. While getting money back feels good, you're essentially giving the government an interest-free loan.

Underwithholding scenario: A single retiree with substantial TSP distributions and Social Security has three income streams but only the annuity is withholding. The single-with-no-adjustments default doesn't account for the other income, and the combined total pushes them into a higher bracket than the annuity alone would indicate.

Either way, submitting an accurate W-4P early in retirement is important. Don't wait until you get a surprise tax bill.

State Tax Withholding

OPM can also withhold state income tax from your annuity, but it's not automatic and the process is separate from federal withholding.

To request state tax withholding, log in to Services Online and look for the "State Tax Withholding" option. Not all states are available through the online system — some require a separate state-specific withholding form mailed to OPM.

If you move to a different state, update your state withholding promptly. OPM continues withholding for your previous state until you make the change, and sorting out withholding credited to the wrong state is a hassle at tax time.

For the nine states with no broad individual income tax (Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming, and New Hampshire), you don't need state withholding on your pension. If you move to one of these states, request that OPM stop state withholding through Services Online.

During Interim Pay

A common frustration: during the 3 to 5 months of interim pay while OPM processes your retirement, only federal income tax is withheld. OPM does not deduct state taxes during interim pay. It also doesn't deduct health insurance (FEHB/PSHB) or life insurance (FEGLI) premiums.

OPM cannot set up state tax withholding for interim payments, so a W-4P will not solve the state-tax gap during that period. For federal withholding, use Services Online or contact OPM about available interim-pay changes; do not assume that a mailed W-4P will change an interim payment. You can also make quarterly estimated tax payments (Form 1040-ES) to cover the state tax gap.

Once your annuity is finalized, OPM retroactively deducts all the accumulated insurance premiums from your first regular payment and applies your W-4P withholding going forward.

When to Adjust

Review your withholding annually, or whenever your situation changes:

• Adding Social Security — if you start collecting Social Security mid-year, your total income goes up but your annuity withholding doesn't change automatically to account for it
• Starting TSP distributions — same issue; another income stream with its own separate withholding
• COLA increase — your gross annuity goes up but the withholding percentage stays the same, so dollar withholding increases proportionally. This is usually fine unless the COLA pushes you into a new bracket
• Moving states — update state withholding and potentially federal withholding if the state tax change affects your overall tax planning

The Taxes on Federal Retirement toolkit includes a withholding coordination worksheet that calculates the combined withholding needed across your OPM annuity, TSP, and Social Security — so you can fill out the W-4P with the right numbers instead of guessing.