Calculator Verification

Single, over 65. Net benefits 1,500; taxable pension 17,000 plus interest 700 = 17,700 other income; no tax-exempt interest. Worksheet A line E is 18,450, at or below the 25,000 base amount, so none of the benefits are taxable.

Figures taken directly from: IRS Publication 915 (2025), Worksheet A example and filled-in Worksheet A, page 4

Single. Pension 18,600 plus wages 9,400 plus interest 990 = 28,990 (worksheet line 3). Benefits 5,980. Worksheet line 19 taxable benefits 2,990. Exercises the first band and the half-the-benefits cap: line 15 takes the smaller of line 2 (2,990) and line 14 (3,490).

Figures taken directly from: IRS Publication 915 (2025), Example 1 and filled-in Worksheet 1, page 7

MFJ, tier 1 SSEB railroad benefits of 10,000 treated as social security. Worksheet line 3 is 40,500 (pension 38,000 plus 2,500 Schedule B interest). Line 8 is 45,500, above the 44,000 second threshold. Line 19 taxable benefits 6,275, being 5,000 in the 50 percent tier plus 1,275 in the 85 percent tier. Exercises the second min cap: line 15 takes the smaller of line 2 (5,000) and line 14 (6,000).

Figures taken directly from: IRS Publication 915 (2025), Example 3 and filled-in Worksheet 1, page 9

Provisional income 24,000 = 14,000 other + half of 20,000 benefits. Below the 25,000 base amount, so no benefits are taxable.

Derived from: IRC 86(a); IRS Publication 915

Provisional 30,000 = 20,000 + half of 20,000. Taxable = lesser of half the excess over 25,000 (2,500) and half the benefits (10,000). Both limbs are halved.

Derived from: IRC 86(a)(1)

Provisional exactly 32,000 = 20,000 + half of 24,000. At the base amount, not over it, so nothing is taxable. Pins the boundary as inclusive.

Derived from: IRC 86(a); IRS Publication 915

Provisional 215,000 is far above the second threshold, so taxable benefits are capped at 85 percent of 30,000.

Derived from: IRC 86(a)(2)

DERIVED from IRS Example 2, not a verbatim reproduction, which is why it is not labelled sourceExample. The publication's worksheet line 3 is 29,750 (pension 15,500, wages 14,000, interest 250) and line 7 removes a 1,000 deductible IRA contribution, giving line 8 of 31,550 against the 32,000 joint base amount, so none of the 5,600 in benefits is taxable. The calculator does not collect above-the-line adjustments, so otherIncome is entered as 28,750, being line 3 minus line 7. That reproduces the IRS's line 8 and its result, but 28,750 is a figure the IRS never printed. The verification page must not attribute it to them.

Derived from: Derived from IRS Publication 915 (2025), Example 2 and filled-in Worksheet 1, page 8

irmaaMagi = otherOrdinaryIncome (109,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a single filer as "More than $109,000 but less than or equal to $137,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 109,000 is not more than 109,000, so tier 0 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (109,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a single filer as "More than $109,000 but less than or equal to $137,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 109,001 is one dollar more than 109,000, the first amount the band reaches, so tier 1 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (109,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a single filer as "More than $109,000 but less than or equal to $137,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 109,002 is inside the band, so tier 1 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (218,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a couple filing jointly as "More than $218,000 but less than or equal to $274,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 218,000 is not more than 218,000, so tier 0 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (218,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a couple filing jointly as "More than $218,000 but less than or equal to $274,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 218,001 is one dollar more than 218,000, the first amount the band reaches, so tier 1 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (218,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 1 band for a couple filing jointly as "More than $218,000 but less than or equal to $274,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 218,002 is inside the band, so tier 1 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (137,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a single filer as "More than $137,000 but less than or equal to $171,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 137,000 is not more than 137,000, so tier 1 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (137,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a single filer as "More than $137,000 but less than or equal to $171,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 137,001 is one dollar more than 137,000, the first amount the band reaches, so tier 2 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (137,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a single filer as "More than $137,000 but less than or equal to $171,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 137,002 is inside the band, so tier 2 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (274,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a couple filing jointly as "More than $274,000 but less than or equal to $342,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 274,000 is not more than 274,000, so tier 1 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (274,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a couple filing jointly as "More than $274,000 but less than or equal to $342,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 274,001 is one dollar more than 274,000, the first amount the band reaches, so tier 2 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (274,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 2 band for a couple filing jointly as "More than $274,000 but less than or equal to $342,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 274,002 is inside the band, so tier 2 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (171,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a single filer as "More than $171,000 but less than or equal to $205,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 171,000 is not more than 171,000, so tier 2 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (171,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a single filer as "More than $171,000 but less than or equal to $205,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 171,001 is one dollar more than 171,000, the first amount the band reaches, so tier 3 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (171,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a single filer as "More than $171,000 but less than or equal to $205,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 171,002 is inside the band, so tier 3 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (342,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a couple filing jointly as "More than $342,000 but less than or equal to $410,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 342,000 is not more than 342,000, so tier 2 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (342,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a couple filing jointly as "More than $342,000 but less than or equal to $410,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 342,001 is one dollar more than 342,000, the first amount the band reaches, so tier 3 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (342,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 3 band for a couple filing jointly as "More than $342,000 but less than or equal to $410,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 342,002 is inside the band, so tier 3 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (205,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a single filer as "More than $205,000 but less than $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 205,000 is not more than 205,000, so tier 3 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (205,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a single filer as "More than $205,000 but less than $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 205,001 is one dollar more than 205,000, the first amount the band reaches, so tier 4 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (205,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a single filer as "More than $205,000 but less than $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 205,002 is inside the band, so tier 4 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (410,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a couple filing jointly as "More than $410,000 but less than $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 410,000 is not more than 410,000, so tier 3 still applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (410,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a couple filing jointly as "More than $410,000 but less than $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 410,001 is one dollar more than 410,000, the first amount the band reaches, so tier 4 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (410,002), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 4 band for a couple filing jointly as "More than $410,000 but less than $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 410,002 is inside the band, so tier 4 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (499,999), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a single filer as "Greater than or equal to $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 499,999 is less than 500,000, so it stays in tier 4.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (500,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a single filer as "Greater than or equal to $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 500,000 is exactly 500,000. This is the ONLY band published as "greater than or equal to" rather than "more than", so the threshold amount itself falls in tier 5, not tier 4. Encoding this row like the four above it is a known way to get the top tier wrong by one dollar.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (500,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a single filer as "Greater than or equal to $500,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 500,001 is inside the band, so tier 5 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (749,999), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a couple filing jointly as "Greater than or equal to $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 749,999 is less than 750,000, so it stays in tier 4.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (750,000), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a couple filing jointly as "Greater than or equal to $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 750,000 is exactly 750,000. This is the ONLY band published as "greater than or equal to" rather than "more than", so the threshold amount itself falls in tier 5, not tier 4. Encoding this row like the four above it is a known way to get the top tier wrong by one dollar.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

irmaaMagi = otherOrdinaryIncome (750,001), with no Social Security, preferential income or tax-exempt interest to add. The Federal Register notice states the tier 5 band for a couple filing jointly as "Greater than or equal to $750,000" (90 FR 52063; SSA restates the same table at POMS HI 01101.020). 750,001 is inside the band, so tier 5 applies.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

Single, all income as long-term capital gains of 200,000, no other income, age 60 (below 65, so no senior addition or bonus; standard deduction = 16,100). AGI = MAGI (no muni, no SS) = 200,000. Taxable income = 200,000 - 16,100 = 183,900, all preferential since raw LTCG (200,000) exceeds taxable income, so per the QDCGT worksheet rule preferential is capped at taxable income and ordinary = 0. Stacking the capital-gains brackets (0% to 49,450 single / 98,900 MFJ, then 15%) against that taxable income gives federal income tax of 20,167.5. NIIT: MAGI 200,000 vs threshold 200,000 gives excess 0; base = min(netInvestmentIncome, excess) = 0; NIIT = 0 * 0.038 = 0. totalFederalTax = 20,167.5 + 0 = 20167.5.

Derived from: IRC 1411(b)

Single, all income as long-term capital gains of 210,000, no other income, age 60 (below 65, so no senior addition or bonus; standard deduction = 16,100). AGI = MAGI (no muni, no SS) = 210,000. Taxable income = 210,000 - 16,100 = 193,900, all preferential since raw LTCG (210,000) exceeds taxable income, so per the QDCGT worksheet rule preferential is capped at taxable income and ordinary = 0. Stacking the capital-gains brackets (0% to 49,450 single / 98,900 MFJ, then 15%) against that taxable income gives federal income tax of 21,667.5. NIIT: MAGI 210,000 vs threshold 200,000 gives excess 10,000; base = min(netInvestmentIncome, excess) = 10,000; NIIT = 10,000 * 0.038 = 380. totalFederalTax = 21,667.5 + 380 = 22047.5.

Derived from: IRC 1411(b)

MFJ, all income as long-term capital gains of 250,000, no other income, age 60 (below 65, so no senior addition or bonus; standard deduction = 32,200). AGI = MAGI (no muni, no SS) = 250,000. Taxable income = 250,000 - 32,200 = 217,800, all preferential since raw LTCG (250,000) exceeds taxable income, so per the QDCGT worksheet rule preferential is capped at taxable income and ordinary = 0. Stacking the capital-gains brackets (0% to 49,450 single / 98,900 MFJ, then 15%) against that taxable income gives federal income tax of 17,835. NIIT: MAGI 250,000 vs threshold 250,000 gives excess 0; base = min(netInvestmentIncome, excess) = 0; NIIT = 0 * 0.038 = 0. totalFederalTax = 17,835 + 0 = 17835.

Derived from: IRC 1411(b)

MFJ, all income as long-term capital gains of 260,000, no other income, age 60 (below 65, so no senior addition or bonus; standard deduction = 32,200). AGI = MAGI (no muni, no SS) = 260,000. Taxable income = 260,000 - 32,200 = 227,800, all preferential since raw LTCG (260,000) exceeds taxable income, so per the QDCGT worksheet rule preferential is capped at taxable income and ordinary = 0. Stacking the capital-gains brackets (0% to 49,450 single / 98,900 MFJ, then 15%) against that taxable income gives federal income tax of 19,335. NIIT: MAGI 260,000 vs threshold 250,000 gives excess 10,000; base = min(netInvestmentIncome, excess) = 10,000; NIIT = 10,000 * 0.038 = 380. totalFederalTax = 19,335 + 380 = 19715.

Derived from: IRC 1411(b)

Single, age 60, LTCG 65,549, no conversion, no other income. Standard deduction 16,100 (age<65, no senior addition). AGI = 65,549; taxable income = 65,549 - 16,100 = 49,449. Raw LTCG (65,549) exceeds taxable income, so preferential = taxable income = 49,449, ordinary = 0. The single 0% capital-gains band runs threshold 0 to 49,450 (federalCapGainsBracketsSingle), so all 49,449 dollars fall inside the 0% band (49,449 <= 49,450): tax = 49,449 * 0 = 0. MAGI 65,549 is far below the 200,000 NIIT threshold, so NIIT = 0. totalFederalTax = 0.

Derived from: IRC 1(h); IRS Rev. Proc. 2025-32

Same household as ltcg-0-to-15-just-under-ceiling, plus a 10,000 conversion. AGI = 65,549 + 10,000 = 75,549; taxable income = 75,549 - 16,100 = 59,449. Raw LTCG (65,549) still exceeds taxable income, so preferential = 59,449, ordinary = 0 (the QDCGT worksheet rule: the conversion raises AGI and therefore taxable income, but with preferential income this large it is still the preferential dollars that occupy the stack, now reaching higher). Of the 59,449 preferential dollars, the first 49,450 sit in the 0% band (tax 0) and the remaining 59,449 - 49,450 = 9,999 sit in the 15% band: 9,999 * 0.15 = 1,499.85. MAGI 75,549 is still below the NIIT threshold, so NIIT = 0. totalFederalTax = 1,499.85.

Derived from: IRC 1(h); IRS Rev. Proc. 2025-32

Single, age 65, otherOrdinaryIncome 75,000 and nothing else, so AGI = irmaaMagi = 75,000. IRC 151(d)(5) as added by the OBBBA sets the deduction at 6,000 per qualified individual and begins the phaseout at 75,000 of modified AGI for a single filer, at 6 percent of the excess. At exactly the threshold the excess is zero, so the reduction is zero and the full 6,000 is allowed. standardOrItemized = the 2026 single standard deduction 16,100 plus the age-65 addition 2,050 (both Rev. Proc. 2025-32) plus 6,000 = 24,150.

Derived from: IRC 151(d)(5)(B) as added by OBBBA

Single, age 65, otherOrdinaryIncome 175,000, so AGI = irmaaMagi = 175,000. Reduction = (175,000 - 75,000) * 0.06 = 100,000 * 0.06 = 6,000, exactly equal to the 6,000 bonus, so the bonus is fully phased out (max(0, 6,000-6,000) = 0). standardOrItemized = standardDeductionSingle 16,100 + additionalDeduction65Single 2,050 + 0 = 18,150.

Derived from: IRC 151(d)(5)(B) as added by OBBBA

Single, age 60 (below 65, standard deduction only, 16,100), otherOrdinaryIncome 28,500, no preferential or SS income, so taxable income = 28,500 - 16,100 = 12,400, exactly the federalBracketsSingle threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 1,240.

Derived from: IRS Rev. Proc. 2025-32

Single, age 60 (below 65, standard deduction only, 16,100), otherOrdinaryIncome 66,500, no preferential or SS income, so taxable income = 66,500 - 16,100 = 50,400, exactly the federalBracketsSingle threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 5,800.

Derived from: IRS Rev. Proc. 2025-32

Single, age 60 (below 65, standard deduction only, 16,100), otherOrdinaryIncome 121,800, no preferential or SS income, so taxable income = 121,800 - 16,100 = 105,700, exactly the federalBracketsSingle threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 17,966.

Derived from: IRS Rev. Proc. 2025-32

MFJ, age 60 (below 65, standard deduction only, 32,200), otherOrdinaryIncome 57,000, no preferential or SS income, so taxable income = 57,000 - 32,200 = 24,800, exactly the federalBracketsMFJ threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 2,480.

Derived from: IRS Rev. Proc. 2025-32

MFJ, age 60 (below 65, standard deduction only, 32,200), otherOrdinaryIncome 133,000, no preferential or SS income, so taxable income = 133,000 - 32,200 = 100,800, exactly the federalBracketsMFJ threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 11,600.

Derived from: IRS Rev. Proc. 2025-32

MFJ, age 60 (below 65, standard deduction only, 32,200), otherOrdinaryIncome 243,600, no preferential or SS income, so taxable income = 243,600 - 32,200 = 211,400, exactly the federalBracketsMFJ threshold. The tax function only applies a bracket rate to income above that bracket start (income <= start stops before that bracket), so income exactly at the threshold is taxed entirely by the lower brackets. No investment income means NIIT = 0, so totalFederalTax = ordinary tax = 35,932.

Derived from: IRS Rev. Proc. 2025-32

MFJ, both 65+, AGI 160,000, itemizing 45,000. IRC 151(d)(5)(C) allows the senior deduction under section 151, and IRC 63(d) defines itemized deductions as everything OTHER than above-the-line deductions, the standard deduction and the section 151 deductions - so it is neither, and an itemizer receives it too. Excess over the joint threshold is 10,000, per-person reduction 600, per-person bonus 5,400, two seniors = 10,800. Total deduction 45,000 + 10,800 = 55,800.

Derived from: IRC 151(d)(5)(C); IRC 63(d); CMS Medicare Part B and Part D IRMAA, 2026

Same household aged 60/59. No qualified individual, so the itemized total stands alone.

Derived from: IRC 151(d)(5)(C); IRC 63(d); CMS Medicare Part B and Part D IRMAA, 2026

MFJ, AGI 342,001, one dollar into the tier 3 joint band, both spouses enrolled. 90 FR 52063 publishes the standard Part B premium as 202.90 and the tier 3 total as 527.50, giving a Part B IRMAA of 324.60, which the notice states directly. Part D IRMAA is 60.40. Per beneficiary that is (324.60 + 60.40) x 12 = 4,620.00; two beneficiaries = 9,240.00.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

Single, AGI 205,001, one dollar into the tier 4 band, one beneficiary. 90 FR 52063 gives a tier 4 Part B IRMAA of 446.30 (total 649.20 less the 202.90 standard) and a Part D IRMAA of 83.30. (446.30 + 83.30) x 12 = 6,355.20.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

MFJ, AGI 750,001, the top band. 90 FR 52063 gives a tier 5 Part B IRMAA of 487.00 (total 689.90 less the 202.90 standard) and a Part D IRMAA of 91.00. (487.00 + 91.00) x 12 = 6,936.00 each, 13,872.00 for two beneficiaries.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

Same top-tier MAGI, nobody on Medicare. IRMAA is levied per beneficiary, so a household with no beneficiaries owes nothing however high its MAGI.

Derived from: CMS, Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026, 90 FR 52063 (Nov. 19, 2025)

Single, 90,000 ordinary income and 40,000 of tax-exempt interest. IRC 103 keeps muni out of gross income and therefore out of AGI, so AGI is 90,000. IRMAA MAGI adds it back: 130,000. That is the one income type where the two figures diverge.

Derived from: IRC 151(d)(5)(C); IRC 63(d); CMS Medicare Part B and Part D IRMAA, 2026