Verified 2026-07-16
Methodology and sources
RMD Compass is deterministic arithmetic, not a recommendation system. This page publishes the formulas, inputs, constants, sources, tests, and known limits behind each result.
Formulas
Required minimum distribution
RMD = prior Dec 31 tax-deferred balance ÷ the Uniform Lifetime Table factor for the owner’s age. Results use positive-value half-up rounding to cents.
Applicable RMD age
Birth years through 1948 use 70½; 1949–1950 use 72; 1951–1959 use 73; and 1960 or later use 75. The projection checks applicable age before calculating an RMD.
Taxable Social Security
Provisional income = other ordinary income + 50% of Social Security. Between the lower and upper threshold, up to 50% is taxable; above the upper threshold, the IRS worksheet adds 85% of the excess plus the lower-tier amount, capped at 85% of benefits.
Federal income tax
Taxable income = ordinary income + taxable Social Security − standard deduction, floored at zero. Tax is the sum of each occupied bracket width multiplied by that bracket rate; marginal rate and room to the next bracket are reported separately.
IRMAA
Approximate MAGI = projected adjusted gross income. The tier is the highest 2026 lower bound crossed, and annual surcharge = (monthly Part B surcharge + monthly Part D surcharge) × 12 per person; actual Medicare assessment generally uses a two-year lookback.
Projection order
For each year, the planner computes the full RMD first, treats QCD as part of that required withdrawal, then converts only remaining balance. Growth is applied at year end to the balance remaining after the RMD and conversion.
Bracket-fill conversions
Conversion = selected bracket’s upper threshold − taxable income before conversion, floored at zero and capped at the balance left after RMD. Taxable Social Security is recalculated after the conversion.
2026 constants
All figures below are held in one engine constants object and carry source comments in the source file.
RMD ages
| Birth years | Applicable age |
|---|---|
| Through 1948 | 70½ |
| 1949–1950 | 72 |
| 1951–1959 | 73 |
| 1960 and later | 75 |
Source: Congressional Research Service RMD rules.
Uniform Lifetime Table
| Age | Factor |
|---|---|
| 72 | 27.4 |
| 73 | 26.5 |
| 74 | 25.5 |
| 75 | 24.6 |
| 76 | 23.7 |
| 77 | 22.9 |
| 78 | 22.0 |
| 79 | 21.1 |
| 80 | 20.2 |
| 81 | 19.4 |
| 82 | 18.5 |
| 83 | 17.7 |
| 84 | 16.8 |
| 85 | 16.0 |
| 86 | 15.2 |
| 87 | 14.4 |
| 88 | 13.7 |
| 89 | 12.9 |
| 90 | 12.2 |
| 91 | 11.5 |
| 92 | 10.8 |
| 93 | 10.1 |
| 94 | 9.5 |
| 95 | 8.9 |
| 96 | 8.4 |
| 97 | 7.8 |
| 98 | 7.3 |
| 99 | 6.8 |
| 100 | 6.4 |
| 101 | 6.0 |
| 102 | 5.6 |
| 103 | 5.2 |
| 104 | 4.9 |
| 105 | 4.6 |
| 106 | 4.3 |
| 107 | 4.1 |
| 108 | 3.9 |
| 109 | 3.7 |
| 110 | 3.5 |
| 111 | 3.4 |
| 112 | 3.3 |
| 113 | 3.1 |
| 114 | 3.0 |
| 115 | 2.9 |
| 116 | 2.8 |
| 117 | 2.7 |
| 118 | 2.5 |
| 119 | 2.3 |
| 120 and over | 2.0 |
Source: IRS Publication 590-B, Table III.
Federal ordinary-income brackets
| Rate | Single threshold | MFJ threshold |
|---|---|---|
| 10% | $0 | $0 |
| 12% | $12,400 | $24,800 |
| 22% | $50,400 | $100,800 |
| 24% | $105,700 | $211,400 |
| 32% | $201,775 | $403,550 |
| 35% | $256,225 | $512,450 |
| 37% | $640,600 | $768,700 |
Threshold means taxable income over the listed amount. Source: IRS 2026 tax inflation adjustments.
Standard deduction
| Status | Base | Age-65 addition |
|---|---|---|
| Single | $16,100 | $2,050 |
| Married filing jointly | $32,200 | $1,650 per eligible spouse |
Source: IRS 2026 tax inflation adjustments. Blindness is not modeled.
IRMAA tiers
| Tier | Single lower bound | MFJ lower bound | Part B / mo. | Part D / mo. | Annual surcharge |
|---|---|---|---|---|---|
| Standard | $0 | $0 | $0.00 | $0.00 | $0.00 |
| 1 | $109,000 | $218,000 | $81.20 | $14.50 | $1148.40 |
| 2 | $137,000 | $274,000 | $202.90 | $37.50 | $2884.80 |
| 3 | $171,000 | $342,000 | $324.60 | $60.40 | $4620.00 |
| 4 | $205,000 | $410,000 | $446.30 | $83.30 | $6355.20 |
| 5 | $500,000 | $750,000 | $487.00 | $91.00 | $6936.00 |
Standard Part B premium: $202.90 monthly. Lookback: 2 years. Source: CMS 2026 Medicare Part B premiums fact sheet; the primary page blocked direct retrieval during research and values were cross-checked against independent published tables.
QCD, Social Security, and NIIT
| Constant | Single | MFJ |
|---|---|---|
| QCD age / annual limit | 70½ / $111,000 | 70½ / $111,000 per person |
| SS provisional thresholds | $25,000 / $34,000 | $32,000 / $44,000 |
| Maximum taxable SS | 85% | 85% |
| NIIT rate / MAGI threshold | 3.8% / $200,000 | 3.8% / $250,000 |
Sources: IRS IRA FAQs for the QCD age rule, 2026 QCD limit cross-verification, SSA policy research, and IRS NIIT questions and answers. NIIT is flagged but not calculated.
Published golden test cases
- Age 75, $500,000 balance: factor 24.6; RMD $20,325.20.
- Age 73, $600,000 balance: factor 26.5; RMD $22,641.51.
- Age 80, $1,200,000 balance: factor 20.2; RMD $59,405.94.
- IRS Pub 590-B: age 75, $100,000 balance: $4,065.04, or $4,065 rounded.
- MFJ taxable income $100,800: federal tax $11,600; at $100,000, $800 remains before the 22% bracket.
- Single MAGI $109,000 is standard IRMAA; $109,001 is tier 1 with $1,148.40 annual surcharge. MFJ $342,000 is tier 2; $342,001 is tier 3.
- Single Social Security $30,000 plus $40,000 other income: taxable benefit $22,350. With $20,000 benefit and no other income: $0.
- Applicable ages: birth year 1959 → 73; 1960 → 75; 1952 → 73.
- Projection invariants: conversions never exceed post-RMD balance, balances never go negative, QCD stays within its statutory and withdrawal limits, and QCD is zero below age 70½.
Limitations
- Joint Life and Last Survivor Table math is not implemented; the Uniform Lifetime Table overstates RMDs when the sole-beneficiary spouse is more than 10 years younger.
- State income taxes are excluded.
- Long-term capital-gain and qualified-dividend stacking are excluded.
- IRMAA MAGI is approximated with projected AGI and excludes tax-exempt interest and other MAGI adjustments.
- The April 1 first-RMD deferral is noted but not moved into the following tax year.
- The model assumes constant other income, Social Security, and return and holds 2026 federal thresholds constant across projected years.
- For MFJ, one age-65 additional standard deduction is modeled because spouse age is not collected.
Privacy architecture
The calculator engine executes in the browser. Inputs are held only in page memory and are not sent, persisted, analyzed, or attached to an account; there is no email capture or login.
Changelog
- 2026-07-16 · v1.0
- Initial 2026 constants, Uniform Lifetime Table, tax and Social Security engine, IRMAA timing flags, QCD modeling, multi-year plan, and print sheet.