Claude Sonnet 5.5 (effort default (no --effort flag) · thinking on) on Progressive tax on fictional brackets, and pre-tax vs after-tax savings comparison

AClaude Sonnet 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-20 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.06
Wall time: 21s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Progressive tax on fictional brackets, and pre-tax ("traditional") vs after-tax ("Roth") savings `input.json` contains a **fictional** tax system (brackets and standard deductions per filing status), a list of incomes to tabulate, and savings scenarios. Write `solve.py` (Python 3 standard library only) so that `python solve.py input.json answer.json` computes the answers below. Use only the numbers in the input. We re-run it on fresh inputs, so do not hard-code anything. ## Rules 1. Taxable income = max(0, gross income - `standard_deduction[filing]`). 2. Brackets for a filing status are a list of `[lower_bound, rate]` sorted by bound. Rate j applies to the part of taxable income above `lower_bound_j` and up to `lower_bound_{j+1}` (the last bracket has no upper bound). Tax = sum over brackets. 3. Marginal rate = the rate of the last bracket whose lower bound is strictly below taxable income; if taxable income is 0, the first bracket's rate. 4. `tax_table`: for each `[filing, income]` in input order output `{"filing", "income", "tax", "effective_rate", "marginal_rate"}`; effective_rate = tax / income (0 when income is 0), 6 decimals. 5. Scenarios (each has `name`, `filing`, `wages`, `contribution`, `years`, `growth`, `retire_filing`, `retire_other_income`): - `tax_now_traditional` = tax on (wages - contribution); `tax_now_roth` = tax on wages; `tax_saved_now` = their difference; `marginal_rate_now` = marginal rate (rule 3) at the taxable income of (wages - contribution). - `traditional_balance` F = contribution * (1 + growth) ** years. `withdrawal_tax` = tax(retire_other_income + F) - tax(retire_other_income), both with `retire_filing`, taken as one withdrawal in a single year. `traditional_after_tax` = F - withdrawal_tax. - Same out-of-pocket cost: the after-tax account receives (contribution - tax_saved_now), so `roth_after_tax` = (contribution - tax_saved_now) * (1 + growth) ** years. - `winner` = "traditional" or "roth", whichever after-tax value is larger, or "tie" if they differ by less than 0.005. 6. Round money to 2 decimals and rates to 6 only when writing (bracket rates are written as given). ## Output `answer.json`: `{"tax_table": [...], "scenarios": [{"name", "tax_now_traditional", "tax_now_roth", "tax_saved_now", "marginal_rate_now", "traditional_balance", "withdrawal_tax", "traditional_after_tax", "roth_after_tax", "winner"}, ...]}` in input order. ## Scoring Hidden checks (partial credit = fraction passed; all must pass), money within 0.011, rates within 0.000001, winners exact: `tax_table_amounts`, `effective_and_marginal`, `scenario_tax_now`, `scenario_future_values`, `scenario_winners` on the given input; `fresh_run_1`, `fresh_run_2`: the whole answer on fresh inputs (tolerance 0.011). Each run has a 60-second limit.

Incomes placed exactly on bracket boundaries test the strict marginal-rate rule; the equal out-of-pocket comparison and the lump-withdrawal tax at retirement decide winners. Original benchmark task written for usecaserank.com (not based on a specific public post). Headless, offline run on a reproducible fixture. Each run's notes say how its cost was measured (estimates are marked).

These are synthetic test cases for comparing AI models, not financial advice.

Success criteria: 1. tax_table_amounts 2. effective_and_marginal 3. scenario_tax_now 4. scenario_future_values 5. scenario_winners 6. fresh_run_1 7. fresh_run_2

Setup notes: Use Case Scout batch 9 case j05-tax-brackets-roth-vs-traditional (offline fixture). Prepared with batch9/prepare.sh; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored with the scout's scorer: `python score.py WORKDIR KEYDIR`. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Claude Code's own reported cost for claude-sonnet-5.5: $0.057337. Score: 7/7. Cost is an ESTIMATE: measured tokens x pricing.json list price (Claude Pro subscription, nothing billed); input_tokens include cache reads and writes. Single run.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost: $0.06
Wall time: 21s
Human step-ins: 0
Turns: 4

Model usage
Model	Input tok	Output tok	Cost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking on	81,255	1,451	$0.06

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Sonnet 5.5 (anthropic/claude-sonnet-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: 1. tax_table_amounts 2. effective_and_marginal 3. scenario_tax_now 4. scenario_future_values 5. scenario_winners 6. fresh_run_1 7. fresh_run_2
Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Automated checks

Trust 80% comes from these checks (how Trust % works).

Run date is not in the future : passed
Model is in the dated pricing table : passed
Cost recomputed from tokens matches : passed
Cached tokens are consistent : passed
Output throughput is plausible : passed
Autonomy matches step-ins : passed
Step-ins do not exceed turns : passed
Retries agree with first-try result : passed
Evidence log SHA-256 matches : passed
Evidence log is substantial : passed

Evidence log

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  "result": "I wrote `solve.py` and ran it on `input.json`. It produced `answer.json` with 12 `tax_table` rows and 6 scenarios.\n\nI only looked at the start of the output. The first rows look plausible. For example, 28,080 single comes to 998.40 tax at the 8% marginal rate. I haven't checked the scenario numbers or the winners by hand, and I haven't tested it on any other input.\n\nThe script uses only the standard library and reads the brackets and deductions from the input, so nothing is hard-coded. The machine has no `python` command, so run it as `python3 solve.py input.json answer.json`.",
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