Is my Social Security taxable if I have a FERS pension?

By the OnPAR Federal Retirement Education editorial team · Last updated November 9, 2026

Related: Social Security for FERS employees · How a FERS pension is taxed · Pension and TSP taxes in 2026 · Retirement income sources

Short answer: It can be, and having a FERS pension makes that more likely. The IRS compares your income plus half of your Social Security with a base amount: $25,000 if you are single, $32,000 if married filing jointly. Above that, up to 50% of your benefits can be taxable, and above $34,000 single or $44,000 joint, up to 85% can be taxable [1] [2]. Your taxable pension and traditional TSP withdrawals count as income in that test [1]. Social Security is never more than 85% taxable [1]. This page is education, not tax advice.

1. The test the IRS uses

You add up (a) one-half of your Social Security benefits and (b) all your other income, including tax-exempt interest. If the total is more than your base amount, part of your benefits may be taxable [1]. The base amounts are [1]:

If you file jointly you combine both spouses’ income and benefits, even if only one of you gets Social Security [2].

2. What counts as “other income” for a federal retiree

• Your taxable FERS pension. Only the taxable part counts. The small tax-free return of your contributions is not income (see how a FERS pension is taxed) [1] [3].
• Traditional TSP withdrawals are taxed as ordinary income when you take them [3], so they raise this total.
• Qualified Roth TSP withdrawals are not included in income [3], so they don’t add to it.
• Wages, interest, dividends and other taxable income count. So does tax-exempt interest [1].
• The IRS worksheet starts from income lines before the standard deduction, so your deduction doesn’t lower the test [1].

3. Worked examples (made-up numbers)

These follow the steps of IRS Pub 915 Worksheet 1 and the base amounts it lists (the 2025 edition, for returns filed in 2026) [1]. Your own result depends on all your income.

How Example A works: half of $20,000 is $10,000; plus $24,000 pension = $34,000. That is $9,000 over the $25,000 base, and the 50% tier is capped at the $9,000 band, so $9,000 × 50% = $4,500 is taxable [1]. That $4,500 is added to your taxable income; it is then taxed at your regular rate, not a flat 50%.

Example C vs C2 shows why the type of TSP money matters. Pulling $15,000 from a traditional balance pushes taxable Social Security to the 85% cap ($20,400). Taking that same $15,000 from a qualified Roth balance leaves $11,300 taxable, which is $9,100 less income to report. It does not make Roth “better” for everyone. See TSP Roth vs traditional.

4. Is the FERS Supplement or the old WEP/GPO involved?

• FERS employees pay into Social Security. OPM describes FERS as three parts: the basic pension, Social Security and the TSP [4]. See FERS vs TSP and what income you can use in retirement.
• WEP and GPO are repealed. The Social Security Fairness Act repealed the Windfall Elimination Provision and Government Pension Offset for benefits payable after December 2023 [5] [3]. Those rules mainly affected people with pensions from work not covered by Social Security (such as CSRS).
• The FERS Supplement is paid by OPM, not by Social Security. See the FERS Supplement and ask OPM or a tax professional how it will appear on your 1099-R and in this calculation.

5. What about state tax on Social Security?

This is a separate question from the federal test, and it varies by state. For example, California does not tax Social Security benefits [6], and Illinois lets residents subtract Social Security benefits that are taxed federally [7]. Check your own state’s rules.

What to do next

1. When you start benefits, expect a Form SSA-1099 in early February, and your 1099-R from OPM by January 31 [2].
2. Run the IRS worksheet (Worksheet 1 in Pub 915, or the one in the Form 1040 instructions) to see your own number [1] [2].
3. If part of your benefits will be taxable, you can ask for tax to be withheld from Social Security using Form W-4V, add withholding to your pension, or pay estimated tax [2].
4. Look at the order you draw money (pension, traditional TSP, Roth) before you retire.
5. More: Social Security for FERS employees, the Trustees Report and FERS retirees, and pension and TSP taxes in 2026.

Questions and answers

Is Social Security taxable if I get a FERS pension?

It can be. If half of your Social Security plus your other income (taxable pension, traditional TSP withdrawals, wages, interest) is above $25,000 single or $32,000 married filing jointly, part of your benefits may be taxable. Up to 85% can be taxable above $34,000 single or $44,000 joint.

What percent of Social Security is taxable at most?

No more than 85% of your benefits are taxable, according to IRS Pub 915.

Do Roth TSP withdrawals make my Social Security taxable?

Qualified Roth TSP withdrawals are not included in income under IRS Pub 721, so they do not add to the income the IRS uses to test Social Security taxability. Traditional TSP withdrawals do add to it.

Official sources

1. IRS Publication 915: Social Security and Equivalent Railroad Retirement Benefits
2. IRS Topic 423: Social Security and equivalent Railroad Retirement benefits
3. IRS Publication 721: Tax Guide to U.S. Civil Service Retirement Benefits
4. OPM: FERS Information
5. SSA: Social Security Fairness Act (WEP and GPO repeal)
6. California FTB: Social Security
7. Illinois Department of Revenue: Pub-120, Retirement Income

Checked against IRS, OPM, SSA and TSP sources on November 6, 2026. Education only, not legal, tax or financial advice. Your own situation may differ: check with a tax professional, OPM, SSA or your state tax office. Not affiliated with OPM, the IRS, SSA, the TSP or any government agency.