Why Federal Employees Underestimate Taxes in Retirement

Federal Retirement Taxes Under FERS: What’s Taxed, What’s Not, and How to Prepare

Many federal employees assume that after paying into the system for 20, 30, or 40 years, the government will offer a “thank you” in the form of tax-free retirement income.

Unfortunately, that is one of the most expensive assumptions you can make.

While you leave behind Social Security and Medicare payroll taxes (FICA) when you retire, almost all of your FERS retirement income will still be subject to federal income tax—and potentially state income tax as well.

Because federal retirement relies on a “three-legged stool” (your FERS Annuity, Social Security, and the TSP), each income stream comes with its own unique set of IRS rules.

Here is a complete guide to how your FERS retirement income is taxed, what small portions you can receive tax-free, and how to avoid costly tax traps.

The “Three-Legged Stool” Tax Breakdown

How Your FERS Basic Annuity Is Taxed

Your monthly FERS pension check is treated by the IRS as ordinary income. It is taxed at your standard marginal tax bracket, just like the salary you earned while working.

However, there is one small tax break built into your pension: the Tax-Free Recovery Rule.

Throughout your career, a percentage of your basic pay was withheld for your FERS retirement fund:

• FERS (Hired before 2013): Contributed 0.8% of salary

• FERS-RAE (Hired in 2013): Contributed 3.1% of salary

• FERS-FRAE (Hired 2014 or later): Contributed 4.4% of salary

Because these payroll deductions were made with after-tax dollars, the IRS cannot tax those specific dollars again when they are returned to you in retirement.

The IRS “Simplified Method”

OPM does not hand you a tax-free lump sum when you retire. Instead, they use the IRS Simplified Method (IRS Publication 721) to spread your cumulative after-tax contributions across your statistical life expectancy.

The Calculation:

Monthly Tax-Free Amount = Total After-Tax Contributions ÷ Total Expected Months

Example: Suppose you contributed a total of $24,000 into FERS over your career. Based on your age at retirement, the IRS actuarial table expects you to receive payments across 300 months (25 years).

$24,000 ÷ 300 months = $80 per month

In this scenario, the first $80 of every monthly pension check is completely tax-free. The rest of your check is fully taxable.

For most feds hired under the 0.8% system, roughly 90% to 95% of their monthly annuity is taxable. If you were hired under FERS-FRAE (4.4%), a larger percentage of your check—around 10% to 15%—may be tax-free because you contributed significantly more after-tax dollars during your career.

Once you outlive your expected actuarial timeframe and fully recover your original contributions, 100% of your annuity check becomes taxable.

How the FERS Special Retirement Supplement Is Taxed

If you retire under FERS before age 62 with an unreduced pension (e.g., MRA+30 or Age 60 with 20 years), you may receive the FERS Special Retirement Supplement until you reach age 62.

The tax rule for the FERS Supplement is simple: it is 100% taxable as ordinary income.

There are no after-tax contributions attached to the Supplement, so no portion of it is tax-free.

How Your Thrift Savings Plan (TSP) Is Taxed

How your TSP is taxed depends entirely on which bucket you choose to pull from in retirement:

1. Traditional TSP (100% Taxable)

Every dollar you withdraw from your Traditional TSP—both your original pre-tax contributions and decades of compound earnings—is taxed as ordinary income.

• Traditional TSP withdrawals are not taxed at lower capital gains rates.

• By default, the TSP automatically withholds 20% for federal income taxes on recurring and lump-sum distributions, though your actual tax bill may be higher depending on your total income for the year.

2. Roth TSP (100% Tax-Free)

Qualified withdrawals from your Roth TSP are 100% tax-free, including all cumulative earnings and growth.

To qualify for tax-free withdrawals from your Roth TSP, you must meet two conditions:

1. You must be at least age 59½ when taking the distribution.

2. It must be at least 5 years since January 1st of the calendar year in which you made your first Roth TSP contribution.

How Social Security Benefits Are Taxed

A common belief is that Social Security isn’t taxed. But for the vast majority of federal retirees who receive a FERS pension and draw from the TSP, up to 85% of your Social Security benefits will be subject to federal income tax.

The IRS uses a formula called Combined Income (or Provisional Income) to determine how much of your Social Security check is taxable:

Combined Income = Adjusted Gross Income (AGI) + Nontaxable Interest + 50% of Social Security Benefit

Federal Income Thresholds

• Single Filers:

  • Combined Income between $25,000 and $34,000: Up to 50% of Social Security is taxable.

  • Combined Income over $34,000: Up to 85% of Social Security is taxable.

• Married Filing Jointly:

  • Combined Income between $32,000 and $44,000: Up to 50% of Social Security is taxable.

  • Combined Income over $44,000: Up to 85% of Social Security is taxable.

Because your FERS pension alone often pushes your AGI near or above these thresholds, you should build your retirement budget assuming that 85% of your Social Security check will be added to your taxable income.

Don’t Forget State Income Taxes

Federal taxes are only half of the equation. Your state of legal residence determines how much additional tax you owe on your FERS income:

• Tax-Free States: States like Florida, Texas, Nevada, Washington, Wyoming, Alaska, South Dakota, and Tennessee levy no state income tax on pension, TSP, or Social Security income.

• Pension-Exempt States: Several states exempt federal pensions partially or entirely from state income taxes, even if they tax regular wages (e.g., Pennsylvania, Mississippi, and Illinois).

• Fully Taxable States: Many states tax your FERS annuity and TSP withdrawals at standard state income tax rates.

The “IRMAA” Surcharge Trap

When planning large TSP withdrawals (like buying an RV, paying off a mortgage, or funding a dream vacation), beware of triggering IRMAA (Income-Related Monthly Adjustment Amount).

If your Modified Adjusted Gross Income (MAGI) crosses specific thresholds, Medicare imposes a significant monthly surcharge on your Part B and Part D premiums.

Because Medicare uses tax returns from two years prior, a massive Traditional TSP withdrawal at age 63 can trigger unexpected $200+ monthly Medicare surcharges when you turn 65. Drawing from a Roth TSP or executing partial Roth conversions in low-income years can help you fund large purchases without spiking your AGI.

How to Set Up Your Tax Withholding Before You Retire

When you file your FERS retirement application (Form SF-3107):

1. Form W-4P (Pension Withholding): You will submit Form W-4P to tell OPM how much federal income tax to withhold from your monthly annuity check. If you don’t submit one, OPM automatically applies default withholding rules.

2. Form W-4R (TSP Withholding): When setting up TSP distributions, you can adjust your federal tax withholding percentage to match your overall expected tax bracket.

3. State Tax Withholding: OPM allows voluntary state tax withholding for most states, but you must opt in.

The Bottom Line

Your FERS pension, Traditional TSP withdrawals, and Social Security benefits will form the core of your retirement income—and almost all of it will be subject to federal income tax.

The key to keeping more of your hard-earned pension is tax bracket management. By strategically balancing Traditional TSP withdrawals, Roth funds, and income timing, you can minimize your effective tax rate and avoid Medicare surcharges.

Do not wait until tax season of your first retirement year to find out how much you owe. Model your retirement income net of taxes today.