When you turn 65, your standard deduction is no longer a single number. It becomes a stack of three pieces: the base standard deduction everyone gets, the long-standing additional standard deduction for the aged, and — new for tax years 2025–2028 — the OBBBA senior deduction of $6,000 per qualifying filer. The first two are flat. The third phases out at 6% of every dollar of modified adjusted gross income (MAGI) above $75,000 (single) or $150,000 (married filing jointly), which means the exact income range where retirees often do Roth conversions is the range where this deduction is quietly being clawed back. This study decomposes the stack from QuantCalc's tax engine — no hand-typed figures.
The stack, and where it melts: Below the phase-out threshold, turning 65 lifts a single filer's total standard deduction from $16,100 to $24,150 (base $16,100 + aged $2,050 + senior $6,000), and an MFJ couple both 65+ from $32,200 to $47,500. But every dollar of MAGI over $75,000 / $150,000 shaves the senior piece by 6% per qualifying filer, so it is entirely gone by $175,000 of MAGI for a single filer and $250,000 for a couple — leaving only the flat base-plus-aged stack behind.
The three pieces of a retiree's standard deduction
For a filer age 65 or older in 2026, the standard deduction is the sum of three separate provisions:
- The base standard deduction — $16,100 for a single filer, $32,200 for married filing jointly. Everyone gets it, at any age.
- The additional standard deduction for the aged (IRC §63(f)) — an extra $2,050 for an unmarried filer 65+, or $1,650 per spouse 65+ on a joint return. It has existed for decades, is inflation-indexed, and does not phase out.
- The OBBBA senior deduction (§70103 of Pub. L. 119-21) — a new $6,000 per qualifying filer 65+, but only for tax years 2025 through 2028, and only until MAGI phases it out. Married filing separately is not eligible. Unlike the other two, its amount and thresholds are set in nominal dollars with no inflation indexing, so inflation erodes them over the four years it exists.
Because both the aged addition and the senior deduction are granted per qualifying filer, a married couple who are both 65 or older count each provision twice. That is why the tables below model an MFJ household as both spouses at the same age: at 64 neither qualifies, and at 65 or 70 both do — the cleanest way to see the full $12,000 joint senior deduction and its complete phase-out.
The deduction stack, by filing status, age, and MAGI
Every combination of filing status, age, and MAGI on the $50,000–$300,000 grid. The total column is the sum of the three pieces. The last two columns describe the phase-out: how much senior deduction you lose per additional dollar of MAGI, and — as an illustration only — the extra effective marginal rate that lost deduction adds on top of the statutory bracket at that income. Age 64 rows are the pre-eligibility contrast (base deduction only); the 65 and 70 rows are identical, because neither the aged addition nor the senior deduction grows after 65. Click any column to sort; filter by filing status and age.
| Filing | Age | MAGI | Base std deduction | Aged addition | OBBBA senior | Total deduction | Senior lost per extra $1 MAGI | Effective extra marginal rate* |
|---|---|---|---|---|---|---|---|---|
| Single | 64 | $50,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $75,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $100,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $125,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $150,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $175,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $200,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $225,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $250,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $275,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 64 | $300,000 | $16,100 | $0 | $0 | $16,100 | — | — |
| Single | 65 | $50,000 | $16,100 | $2,050 | $6,000 | $24,150 | — | — |
| Single | 65 | $75,000 | $16,100 | $2,050 | $6,000 | $24,150 | 6¢ | +1.32% |
| Single | 65 | $100,000 | $16,100 | $2,050 | $4,500 | $22,650 | 6¢ | +1.32% |
| Single | 65 | $125,000 | $16,100 | $2,050 | $3,000 | $21,150 | 6¢ | +1.32% |
| Single | 65 | $150,000 | $16,100 | $2,050 | $1,500 | $19,650 | 6¢ | +1.44% |
| Single | 65 | $175,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 65 | $200,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 65 | $225,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 65 | $250,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 65 | $275,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 65 | $300,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $50,000 | $16,100 | $2,050 | $6,000 | $24,150 | — | — |
| Single | 70 | $75,000 | $16,100 | $2,050 | $6,000 | $24,150 | 6¢ | +1.32% |
| Single | 70 | $100,000 | $16,100 | $2,050 | $4,500 | $22,650 | 6¢ | +1.32% |
| Single | 70 | $125,000 | $16,100 | $2,050 | $3,000 | $21,150 | 6¢ | +1.32% |
| Single | 70 | $150,000 | $16,100 | $2,050 | $1,500 | $19,650 | 6¢ | +1.44% |
| Single | 70 | $175,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $200,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $225,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $250,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $275,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Single | 70 | $300,000 | $16,100 | $2,050 | $0 | $18,150 | — | — |
| Married Filing Jointly | 64 | $50,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $75,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $100,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $125,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $150,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $175,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $200,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $225,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $250,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $275,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 64 | $300,000 | $32,200 | $0 | $0 | $32,200 | — | — |
| Married Filing Jointly | 65 | $50,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 65 | $75,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 65 | $100,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 65 | $125,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 65 | $150,000 | $32,200 | $3,300 | $12,000 | $47,500 | 12¢ | +2.64% |
| Married Filing Jointly | 65 | $175,000 | $32,200 | $3,300 | $9,000 | $44,500 | 12¢ | +2.64% |
| Married Filing Jointly | 65 | $200,000 | $32,200 | $3,300 | $6,000 | $41,500 | 12¢ | +2.64% |
| Married Filing Jointly | 65 | $225,000 | $32,200 | $3,300 | $3,000 | $38,500 | 12¢ | +2.64% |
| Married Filing Jointly | 65 | $250,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
| Married Filing Jointly | 65 | $275,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
| Married Filing Jointly | 65 | $300,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
| Married Filing Jointly | 70 | $50,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 70 | $75,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 70 | $100,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 70 | $125,000 | $32,200 | $3,300 | $12,000 | $47,500 | — | — |
| Married Filing Jointly | 70 | $150,000 | $32,200 | $3,300 | $12,000 | $47,500 | 12¢ | +2.64% |
| Married Filing Jointly | 70 | $175,000 | $32,200 | $3,300 | $9,000 | $44,500 | 12¢ | +2.64% |
| Married Filing Jointly | 70 | $200,000 | $32,200 | $3,300 | $6,000 | $41,500 | 12¢ | +2.64% |
| Married Filing Jointly | 70 | $225,000 | $32,200 | $3,300 | $3,000 | $38,500 | 12¢ | +2.64% |
| Married Filing Jointly | 70 | $250,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
| Married Filing Jointly | 70 | $275,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
| Married Filing Jointly | 70 | $300,000 | $32,200 | $3,300 | $0 | $35,500 | — | — |
*An illustration only: the senior deduction lost per extra dollar of MAGI (6% per qualifying filer inside the window) valued at the statutory ordinary bracket that applies at that income. It is the extra marginal rate the phase-out adds on top of the bracket, not a separate statutory rate, and it applies only while MAGI sits inside the phase-out window.
Why the phase-out is a stealth marginal-rate increase
The senior deduction does not vanish at a cliff. It bleeds away at 6% of MAGI over the threshold — 6¢ of deduction lost per dollar for a single filer, and 12¢ per dollar for a couple both 65+ (two qualifying filers, each losing 6%). Losing a dollar of deduction is not free: it exposes a dollar that was shielded to your ordinary bracket. So inside the window, every extra dollar of income is taxed at your statutory rate plus the value of the deduction it claws back. The "effective extra marginal rate" column shows that add-on. For a single filer it is small in absolute terms but real; for a couple it is double. The point is not the size of any single figure — it is that the phase-out window silently raises the marginal cost of income in exactly the $75,000–$175,000 (single) / $150,000–$250,000 (MFJ) range.
What this means for Roth-conversion timing
A Roth conversion adds to MAGI in the year you do it. If your MAGI is already inside the senior-deduction phase-out window — or a conversion pushes it there — each converted dollar does two things at once: it is taxed at your ordinary bracket, and it claws back 6% of a dollar of senior deduction per qualifying filer, which is itself taxed at that bracket. That is the marginal-cost bump this study isolates.
To make it concrete at one point: a single filer age 65 with MAGI around $100,000 sits inside the window, where the next dollar of conversion income falls in the 22% statutory bracket and simultaneously costs 6¢ of senior deduction. Valued at that bracket, the clawback adds roughly 1.32% to the marginal rate — so conversion dollars in that window carry an effective marginal rate near 23.32% rather than 22%. That is an illustration at a single point, not a schedule: the exact bump depends on your filing status, how many filers qualify, your bracket, and where in the window each converted dollar lands, and it stacks with other MAGI-linked effects such as IRMAA and Social Security taxation.
The practical takeaway is timing, not avoidance: a conversion that fits under the $75,000 / $150,000 threshold keeps the full senior deduction, while one that runs through the window pays the extra marginal cost on the way. This study measures the deduction stack and its phase-out; it does not compute whether a conversion pays off — that break-even analysis (future vs. current tax rate, by state) lives in the companion pages below, which this page does not duplicate.
CC-BY-4.0 — free for any use including republication and journalism, with attribution to QuantCalc Research.
The senior deduction is temporary. Under current law it applies only to tax years 2025 through 2028. Absent new legislation it disappears entirely after 2028, leaving retirees with just the base standard deduction and the aged addition. Married filing separately is not eligible for it at all. This study reflects the 2026 parameters as encoded in QuantCalc's engine.
Assumptions
- Figures are 2026 amounts: the base standard deduction, the IRC §63(f) additional standard deduction for the aged, and the OBBBA §70103 senior deduction, as encoded in QuantCalc's tax engine.
- The aged addition and the senior deduction are granted per qualifying filer 65+. MFJ rows model both spouses at the stated age, so 65 and 70 count two qualifying filers and 64 counts none.
- The senior deduction phases out at 6% of MAGI over $75,000 (single) / $150,000 (MFJ), per qualifying filer, reaching zero at $175,000 / $250,000 of MAGI.
- "Senior lost per extra $1 MAGI" is a finite difference of the engine's senior-deduction function; the "effective extra marginal rate" values that loss at the statutory ordinary bracket at taxable income (MAGI minus the full stack) and is an illustration, not a separate statutory rate.
- MAGI here is treated as the phase-out base directly; it does not model itemizing (this study assumes the standard deduction is taken), state deductions, or interactions with IRMAA and Social Security taxation, which compound separately.
- The senior deduction is temporary (2025–2028) and married filing separately is ineligible.
Methodology
Source: Every deduction figure on this page is produced by calling frontend/js/calc/federal-tax-2026.js's exported functions — additionalAgedDeduction(filing, age, spouseAge) for the aged addition and seniorDeduction(filing, age, magi, taxYear, spouseAge) for the OBBBA senior deduction (including its 6% MAGI phase-out) — with the base standard deduction read from QCConstants2026.STD_DEDUCTION (constants-2026.js). The illustrative marginal bracket comes from marginalRateAt(taxableIncome, filing). None of these numbers is hand-transcribed into HTML; they are function calls over QuantCalc's canonical client-side tax mirror of the frozen production C engine (backend/src/tax_calculator.c).
Phase-out mechanic: The "senior lost per extra $1 MAGI" column is computed as a finite difference — seniorDeduction(magi) − seniorDeduction(magi + 1) — so it reads the phase-out slope straight off the engine rather than assuming it. It is zero outside the window and the phase-out rate times the qualifying-filer count inside it.
Consistency: The federal-tax-2026.js mirror is checked against the C engine by a JS↔C parity test suite that sweeps a dense grid of inputs and asserts numeric agreement, so this study, the interactive calculator, and the C backend all report the same deduction figures. As an in-generator safeguard, the generator also runs a hand-check: it recomputes one deduction stack (single filer, age 70, $100,000 MAGI) both from the raw constants-2026.js values and from the engine functions, and asserts both equal an independently hand-computed $22,650, aborting on any mismatch.
Reproducibility: Generated by scripts/gen_senior_deduction_study.mjs, which calls into federal-tax-2026.js directly and writes this page plus the CSV/JSON alongside it. Re-running the generator against the same constants file reproduces byte-identical data rows.
Differentiation: QuantCalc's blog mentions the senior deduction in passing within broader tax-change round-ups; this study is the computed treatment — the full deduction stack decomposed by filing status, age, and MAGI, with the phase-out slope and its marginal-rate illustration produced directly from the engine. It does not restate the blog's narrative, and it does not price a Roth conversion (that is the linked planner and break-even study).
Not tax advice: This is reference data for research and planning purposes, not a substitute for professional tax advice. Consult a qualified advisor before making income-timing or conversion decisions based on these figures.
Time your conversions around the phase-out
Knowing where the senior deduction melts away is one input. The Roth Conversion Planner builds a year-by-year schedule that keeps an eye on the MAGI-linked effects — sizing each conversion to the room you actually have.
Plan your Roth conversions →Changelog
- v2026.1 — initial release. 66-row deduction-stack table (2 filing statuses × 3 ages × 11 MAGI steps), generated from
federal-tax-2026.js/constants-2026.js.
Dataset license: CC-BY-4.0. QuantCalc is an independent retirement-planning research project. Not affiliated with, endorsed by, or sponsored by any state or federal agency, including the IRS. Not financial, tax, or legal advice.