APEX-Accounting
- Source
- arxiv.org
- Author
- Julien Benchek, Austin Bennett, Jasmin Kern, Ryan Stevens, Rene Sultan, Charis Ching, Hayley Popiel, Vaibhav Mittal, Felix Mercier, Brendan Foody, Bertie Vidgen
- Date

Context
APEX-Accounting shows how partial progress can conceal unreliable completion. Built by Mercor with Ramp, its private contains 160 expert-authored tasks across ten synthetic company environments, with files and accounting tools. Across nine models, the highest score was 56.4% of grading criteria satisfied (Claude-Fable-5 at its Max setting), averaged over three runs. That measures partial credit within tasks. Benchmark and scoring method.
Full completion was much harder. The highest Pass@8, completing a task at least once in eight attempts, was 21.5% (Muse-Spark-1.1, xHigh); the highest Pass^8, completing it correctly in all eight, was 2.6% (GPT-5.6-Sol, Max+Pro). Those separate measures expose the difference between occasionally producing a complete answer and doing so consistently. Reliability results.
- The is real work, not exam questions: 160 private tasks across 10 simulated worlds, each with an accounting system plus spreadsheets and PDFs. Working accountants authored the tasks, solved them, and wrote the grading rubrics.
- Averages hide the reliability gap. The leading model scores 56.4% on mean criteria over three runs, but no model clears 2.6% at Pass^8, which requires getting the same task right in all eight attempts.
- Even the generous framing is grim: the best Pass@8, meaning at least one of eight attempts is correct, is 21.5%. Roughly four fifths of real accounting tasks are unsolved even when the model gets eight tries.
- Raising the from $1 to $50 lifts scores, yet inside any fixed budget the tasks where the model spends the most score worst. Spending more helps; needing to spend more is a signal the model is lost.
- eval — A repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.
- benchmark — A standard public test set for comparing AI models — the shared scoreboards behind every "model X beats model Y" claim.
- token budget — A cap on how many tokens a task, session, or agent run may consume — the practical control on both cost and how long an agent will grind.
- token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
“We introduce APEX-Accounting, a benchmark built by Mercor in partnership with Ramp, to assess whether frontier models can do the real work of accountants.”
“Across nine frontier models, Claude-Fable-5 (Max) leads with 56.4% Mean Criteria@3, ahead of Muse-Spark-1.1 (xHigh) at 52.6%.”
“No model scores more than 2.6% Pass^8 (GPT-5.6-Sol (Max+Pro)) and the highest Pass@8 is 21.5% (Muse-Spark-1.1 (xHigh)).”
“We experiment with increasing the token budget from $1 to $50 and observe an instance of Simpson's paradox: scores increase as the token budget increases but within a given budget-constrained harness, scores are lower on tasks where the model spends more tokens.”
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