Surge's new benchmark puts agents on 50 expert-built tax assignments (1,789 workspace files, 1,487 of them PDFs) graded at a 95% rubric threshold; the best model, Claude Sonnet 5.5, passes only 10.8%, with the failures concentrated in spotting consequential issues the client never raised — in one case an agent correctly compared two condo sale dates in all five attempts but never flagged the August 2027 deadline after which a $250,000 gain exclusion expires.