Product UpdatesBuilding Sheldon's State Tax Engine: 98% on TaxCalcBench
Deterministic rule engines for California, Illinois, New York, and Virginia - 620 of 630 scored lines on TaxCalcBench, every gap a documented benchmark defect.

Sheldon now prepares Georgia Form 500 resident returns. Plus model fallback, tighter CA and IL calcs, project-scoped search, and cleaner tables.
Georgia is the headline this week. Sheldon can now prepare a Georgia Form 500 resident return. A handful of product updates shipped alongside the state work.
Following the August 5 update, Sheldon now supports Georgia Form 500 for resident returns. Coverage is California, Illinois, New York, Virginia, and Georgia.
Two related calculation updates landed as well this week: California Form 540 and Illinois IL-1040 now print state use tax correctly, and net refundable credits feed into IRC 6654 required annual payment amounts.
Sheldon general availability is expected next week. For early access, contact support.
When you ask a question inside a project chat, document search now looks only at files in that project's folder, so the answer stays on that project instead of mixing in files from the rest of the knowledge base.
When the primary model is at capacity or unavailable, Feather switches to a backup. You still get an answer.
Tables and summaries in Feather's responses are no longer wrapped in code blocks. Same for documents Feather drafts.
That's all for this week. New here? Try Feather free, see pricing, or subscribe to the Feather Tax Brief for weekly IRS guidance. Take care!
Product UpdatesDeterministic rule engines for California, Illinois, New York, and Virginia - 620 of 630 scored lines on TaxCalcBench, every gap a documented benchmark defect.
Product UpdatesA deterministic tax calculator built on a dedicated knowledge base and AI-generated rules - and how it went from 50% to 190/190 on TaxCalcBench.
Product Updates
Written by Sokratis Vidros, Shashi Mittal
Published on August 30, 2026