Federal Retirement Income Tax Estimator (2026)
Federal retirement income — FERS annuity, TSP distributions, Social Security — each has its own tax treatment, and they interact in ways that surprise most retirees. This estimator combines all three using 2026 rules: the IRS Simplified Method for your FERS exclusion ratio, the combined-income test for Social Security taxation, the 2026 standard deduction with age-65 additions, and the OBBBA enhanced senior deduction (§ 60001, Public Law 119-21).
- Standard deduction: $16,100 single / $32,200 MFJ — IRS Rev. Proc. 2025-671
- Additional age-65 deduction: $2,050 single / $1,650 per qualifying spouse (MFJ)1
- OBBBA enhanced senior deduction (2025–2028): $6,000 per person 65+, phases out $75K–$100K MAGI (single) / $150K–$175K (MFJ)2
- First IRMAA tier: $109,000 MAGI single / $218,000 MFJ (based on 2024 income)3
- SS combined-income thresholds: $25K / $34K single; $32K / $44K MFJ — unchanged since 19934
How federal retirees are taxed — the three moving parts
1. FERS annuity — mostly taxable, with a small monthly exclusion
You contributed after-tax dollars to FERS throughout your career. The IRS lets you recover those contributions tax-free using the Simplified Method (IRS Publication 721). Your total after-tax contributions are divided by an "expected payments" factor based on your age at retirement — the result is a small monthly tax-free amount. For most FERS employees, 90–98% of the annuity is taxable.
| Age at retirement | IRS divisor (Table 1, single life) |
|---|---|
| 55 and under | 360 |
| 56–60 | 310 |
| 61–65 | 260 |
| 66–70 | 210 |
| 71 and over | 160 |
Source: IRS Publication 721, Table 1.5 Once you recover your full contributions, 100% of future payments become taxable.
2. Social Security — up to 85% taxable
The IRS tests your combined income (AGI + 50% of SS) against statutory thresholds that have not been adjusted for inflation since 1993. Most federal retirees with a full FERS annuity and Social Security will be above the 85% tier — meaning 85% of their SS benefit is included in AGI and taxed at their marginal rate. For a retiree in the 22% bracket, that's about 18.7 cents of federal tax per dollar of SS benefit.
3. Deductions — including the 2026 OBBBA senior bonus
The 2026 standard deduction is $16,100 (single) / $32,200 (MFJ). At age 65, you add the regular additional deduction ($2,050 single, $1,650 per qualifying spouse MFJ). The OBBBA (signed July 2025) added a separate enhanced deduction of $6,000 per qualifying person 65 or older, available through 2028, that phases out above $75,000 MAGI (single) or $150,000 (MFJ). Combined, a single retiree at age 65 with MAGI below $75,000 can deduct up to $24,150 before reaching taxable income.
Example: GS-13 retiree, single, age 62
High-3 $130,000 · 28 years · Original FERS (0.8%) · annuity $36,400/yr · TSP $20,000/yr · SS $21,000/yr
- FERS exclusion: approx. contributions $24,900 ÷ 260 (age 62 divisor) = $95.80/mo = $1,150/yr tax-free. Taxable annuity = $35,250.
- AGI before SS: $35,250 + $20,000 = $55,250. Combined income = $55,250 + $10,500 = $65,750.
- SS taxation: Combined income $65,750 > $34,000 single threshold → 85% cap applies. Taxable SS = min(85% × $21,000, $4,500 + 85% × $31,750) = min($17,850, $31,488) = $17,850.
- AGI: $55,250 + $17,850 = $73,100. Standard deduction (single, age 62): $16,100. Taxable income: $57,000.
- Federal tax: ≈ $8,400 (effective rate ≈ 11.5%). After-tax monthly from $77,400 gross: ≈ $5,750/mo.
Related tools and guides
- Federal Retirement Tax Guide — full explanation of the exclusion ratio, SS combined income test, IRMAA cliffs, state taxes, and a GS-14 worked example
- FERS Retirement Calculator — model your annuity, supplement, TSP, and Social Security as an integrated income plan
- TSP RMD Calculator — project required minimum distributions year-by-year with IRMAA exposure flags
- FERS Roth Conversion Strategy — use the early-retirement tax window to reduce future TSP RMDs and IRMAA exposure
- FEHB + Medicare Guide — full 2026 IRMAA tier table and Part B premium surcharges by income level
Get your full tax picture modeled
Federal retirement taxes interact in ways a single calculator can't fully capture: annuity exclusion ratio, TSP withdrawal timing, IRMAA cliff management, Roth conversion windows, state residency, estate planning. A fee-only advisor who specializes in federal benefits models all of these together. Free match, no commissions.
Sources
- IRS: Tax Inflation Adjustments for Tax Year 2026 (Rev. Proc. 2025-67) — 2026 standard deduction amounts and income tax brackets.
- IRS: Check Your Eligibility for the New Enhanced Deduction for Seniors — OBBBA § 60001 enhanced senior deduction, phaseout thresholds, and years in effect.
- CMS: 2026 Medicare Parts B, C, and D — 2026 IRMAA Part B surcharge thresholds and premium amounts by income tier.
- IRS Publication 915: Social Security and Equivalent Railroad Retirement Benefits — combined-income test, taxable portion worksheet, $25K/$34K single thresholds.
- IRS Publication 721: Tax Guide to U.S. Civil Service Retirement Benefits — Simplified Method, expected-payments table, annuity exclusion ratio for federal retirees.
Tax values verified against 2026 IRS guidance. FERS contribution rates per OPM. Results are estimates — your actual liability depends on additional factors including itemized deductions, credits, other income sources, and state taxes not modeled here.
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