TSP Withdrawal Strategy Calculator

Federal retirement runs on three income streams — FERS pension, TSP withdrawals, and Social Security. This calculator shows how they fit together, what your TSP needs to cover each year, how long your balance will last, and your estimated federal tax burden in 2026 rates.

How to read your results

Two-phase structure

Most FERS retirements run in two phases. Phase 1 is from your retirement date to when Social Security starts — TSP carries the heaviest load here. Phase 2 is after SS begins — your income sources stack, TSP withdrawals shrink, and the balance often becomes self-sustaining.

Portfolio longevity estimate

The longevity figure assumes you withdraw a constant inflation-unadjusted dollar amount each year while the remaining balance grows at your assumed rate. A balance that generates more in investment returns than you withdraw will never deplete — that's the "sustainable" outcome.

Federal employees with a solid FERS pension often reach Phase 2 with very low TSP withdrawal requirements, making the math look better than it would for someone with no pension. That's one of the underappreciated advantages of the FERS 3-legged stool.

Tax estimates use 2026 federal brackets

The calculator applies the 2026 federal income tax schedule from IRS Rev. Proc. 2025-32: a 10% bracket to $12,400 (single) / $24,800 (MFJ), a 12% bracket to $50,400 / $100,800, and so on. The 2026 standard deduction is $16,100 single / $32,200 MFJ, plus $2,050 additional for single filers 65+ and $1,650 per qualifying senior for MFJ filers.

Social Security taxation uses the provisional income thresholds from IRC §86 — $34,000 (single) / $44,000 (MFJ) for the 85% inclusion tier. These thresholds haven't been adjusted for inflation since 1984, which is why most federal retirees pay tax on 85% of their SS benefit.

State income taxes not included. FERS pension and TSP distributions are fully taxable as ordinary income at the federal level. Roth TSP balances withdrawn in retirement are tax-free.

Key decisions this calculator helps you think through

When to claim Social Security

Delaying Social Security from 62 to 70 increases your benefit by roughly 77% (from 70% to 124% of the FRA amount). That's an 8%/year guaranteed increase — better than most fixed-income alternatives. But it requires your TSP to carry more load during the delay years. Run both scenarios: claiming at 62 vs 70 often shows the same lifetime tax paid, but the TSP longevity picture changes dramatically.

Federal employees with a FERS pension can often afford to delay SS longer than private-sector workers because the pension covers a chunk of base expenses. The FERS supplement (for those retiring before 62) further eases the gap.

The TSP withdrawal rate problem

The "4% rule" (withdraw 4% of your portfolio balance at retirement each year, inflation-adjusted) was built for a 30-year retirement with no pension. Federal employees with a FERS pension are withdrawing far less as a percentage of TSP, which dramatically extends portfolio longevity. A $700K TSP balance with a $60K/yr FERS pension and $30K SS only needs $0–$15K/yr from TSP — that's not a withdrawal rate problem, that's wealth accumulation.

IRMAA: the Medicare income trap

If your combined income in retirement exceeds $109,000 (single) or $218,000 (MFJ) — the 2026 IRMAA threshold — your Medicare Part B premiums increase by roughly $70/month per person above the base premium. Large TSP withdrawals can push you over this cliff. Roth TSP balances and Roth conversions done before age 65 help manage it. See our FEHB + Medicare guide for details.