fb-rmd-0020

status: publishedversion: v1corpus: 2026.9key: computedseverity: medium

Scenario (all facts stipulated)

{
  "account_type": "traditional IRA (owner's lifetime distribution)",
  "age_at_year_end": 96,
  "beneficiary_context": "surviving spouse is not the sole designated beneficiary",
  "note": "The owner attains age 96 by December 31 of the distribution calendar year."
}

Question posed to the model under test

What is the applicable denominator (the Uniform Lifetime Table divisor) for this owner's required minimum distribution for the distribution calendar year? Respond with the numeric value only.

Answer key

8.4 years (tolerance ±0)

Produced by compute rmd.uniform-lifetime-denominator in src/lib/fiduciarybench/keys/index.ts — the stored value is machine-checked against the compute on every build; it cannot drift from its own code.

Rubric

The exact Uniform Lifetime Table entry for age 96.

Cited primary sources (quote-gated)

26 CFR § 1.401(a)(9)-9 · (c) Uniform Lifetime Table

“the Uniform Lifetime Table, sets forth the applicable denominator that applies for lifetime distributions to an employee in situations in which the employee's surviving spouse is not the sole designated beneficiary”

Each quoted passage is exact-matched, after typographic normalization, against the corpus text fetched from the issuing authority (hashes in the corpus manifest). An item whose quote stops matching fails the build.

Verification record

generator: claude-fable (session 2026-09-01)disagreements: 0controls: fb-2026-09-c (3/3 caught)adjudicated by: — (none required or pending)

gemini-3.1-pro-previewagrees the key is correctquote matched

“94 | 9.5 95 | 8.9 96 | 8.4 97 | 7.8” — cfr-1-401a9-9

The scenario specifies that the owner is 96 years old at the end of the year and the surviving spouse is not the sole designated beneficiary. According to the Uniform Lifetime Table in paragraph (c), the applicable denominator for an employee age 96 is 8.4. The key correctly identifies this value.

deepseek-v4-proagrees the key is correctquote matched

“Age of employee | Applicable denominator 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” — cfr-1-401a9-9

The Uniform Lifetime Table applies because the surviving spouse is not the sole designated beneficiary. The table row for age 96 shows an applicable denominator of 8.4, matching the key.

Version history & errata

v1; no errata. Demonstrate a key error and the correction is published here, credited — challenge policy.