TSP Withdrawals and Social Security: How Distributions Affect Your Benefits

TSP Withdrawals Don't Change Your Social Security Benefit

The Social Security Administration calculates your retirement benefit based on your 35 highest years of earnings from covered employment. Traditional or Roth TSP distributions are not wages and are not factored into the benefit formula. Taking $50,000 from your TSP in a given year does not increase or decrease your monthly Social Security check.

This distinction matters because federal retirees sometimes delay TSP withdrawals out of a fear that large distributions will somehow "offset" their Social Security. They won't. Your benefit is locked in based on your earnings record and the age you claim.

The repeal of the Windfall Elimination Provision and Government Pension Offset under the Social Security Fairness Act (signed January 5, 2025) reinforced this principle for public servants. Previously, CSRS employees and others with non-covered government pensions saw their Social Security benefits reduced by these provisions. With both repealed retroactively to January 2024, your Social Security benefit amount is no longer affected by your federal pension — and was never affected by your TSP distributions in the first place.

Where TSP Withdrawals Do Interact with Social Security

While distributions don't change the benefit amount itself, traditional TSP withdrawals create taxable income that interacts with Social Security in two concrete ways.

Combined Income and Benefit Taxation

The IRS uses "combined income" (also called provisional income) to determine how much of your Social Security benefit is subject to federal income tax. The formula:

Combined Income = Adjusted Gross Income + Nontaxable Interest + ½ of Social Security Benefits

Traditional TSP withdrawals are included in your AGI. A large distribution in the same year you begin collecting Social Security can push your combined income above the thresholds where benefits become taxable:

• Below $25,000 (single) or $32,000 (married filing jointly): Social Security benefits are not taxed.
• $25,000 to $34,000 (single) or $32,000 to $44,000 (joint): Up to 50% of benefits are taxable.
• Above $34,000 (single) or $44,000 (joint): Up to 85% of benefits are taxable.

Most federal retirees with a FERS annuity plus TSP distributions will land in the 85% inclusion bracket regardless, because the FERS pension alone pushes combined income above these thresholds for many retirees. But the timing and size of TSP withdrawals can affect exactly how much additional income tax you owe in a given year.

Qualified Roth TSP withdrawals are not included in AGI. If you have a substantial Roth balance, targeting Roth distributions during years when you are also collecting Social Security keeps those withdrawals from inflating your combined income.

Medicare IRMAA Surcharges

The Income-Related Monthly Adjustment Amount applies to Medicare Part B and Part D premiums based on your modified adjusted gross income from two years prior. For 2026, the standard Part B premium is $202.90 per month. IRMAA surcharges kick in when MAGI exceeds $106,000 (single) or $212,000 (joint), and they escalate through five tiers.

A large traditional TSP withdrawal — whether a lump-sum partial distribution, a Roth conversion pulled from the traditional balance, or a total account distribution — raises your MAGI for that tax year. Two years later, that elevated MAGI triggers higher Medicare premiums.

This is the most commonly overlooked interaction between TSP distributions and Social Security-adjacent benefits. A $200,000 traditional TSP distribution in 2026 to fund a home purchase could push your 2028 Part B premium from $202.90 to over $500 per month.

Roth TSP distributions do not count toward MAGI for IRMAA purposes, which makes Roth balances especially valuable for managing healthcare costs in retirement.

Timing TSP Withdrawals Around Your Social Security Claiming Decision

The decision of when to begin Social Security benefits and when to draw from the TSP are linked by cash-flow strategy, not by regulation.

Delaying Social Security increases your benefit. Each year you postpone claiming past your full retirement age (67 for those born after 1959) adds roughly 8% to your monthly benefit through delayed retirement credits, up to age 70.

TSP distributions can fund the delay. Federal retirees who want to maximize their lifetime Social Security benefit often use TSP installment payments or partial withdrawals to cover living expenses between separation and age 70, drawing down the TSP while allowing the Social Security benefit to grow.

This approach works particularly well when combined with a FERS pension that covers a portion of expenses. The TSP fills the remaining gap during the delay period, and the higher Social Security benefit provides a larger guaranteed income stream for life once claimed.

The trade-off is straightforward: every dollar withdrawn from the TSP during the delay period is a dollar no longer growing tax-deferred. Whether the math favors delaying depends on your health, longevity expectations, and the relative sizes of your TSP balance and projected benefit. The TSP Withdrawal & Drawdown Strategy Guide walks through the withdrawal mechanics for setting up this kind of staged drawdown.

The FERS Supplement Earnings Test Is Separate

If you retire before age 62 with the FERS Special Retirement Supplement, the supplement is subject to a Social Security-style earnings test. For 2026, the exempt limit is $24,480 in earned income. Exceeding that threshold permanently reduces the supplement by $1 for every $2 over the limit.

TSP withdrawals, FERS pension payments, and investment income do not count as earned income under this test. Only wages and net self-employment income count. You can take any size TSP distribution without affecting your supplement — a point covered in detail in the post on FERS supplement and TSP withdrawals.

Practical Coordination Strategies

Spread large traditional withdrawals across tax years rather than taking a single lump sum. This keeps combined income more level, potentially keeping more of your Social Security benefit in a lower taxation bracket and avoiding IRMAA spikes.

Target Roth distributions when possible. If you converted traditional balances to Roth within the TSP (available since January 2026) or contributed to Roth TSP during your career, qualified distributions from the Roth side do not show up in AGI, combined income, or MAGI for IRMAA purposes.

Consider the two-year IRMAA lookback before taking a large distribution. If you plan a major Roth conversion or a one-time large withdrawal, model the IRMAA impact two years out. The premium increase can offset some of the tax benefit.

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