Have Claude Opus complete and check several tax returns
Over a week, Opus 5.5 pushed seven tax and amended returns to completion across several people, years and states. The author, a meticulous reviewer, signed with high confidence, and Opus found errors made by earlier tax professionals.
Source
@lastmjs on X · 2026-10-16
Written in our own words. Credit to the original author. Link checked 2026-10-16.
What they did
Over a week, Opus 5.5 pushed seven tax and amended returns to completion across several people, years and states. The author, a meticulous reviewer, signed with high confidence, and Opus found errors made by earlier tax professionals.
Result (as claimed)
7 returns completed; errors found in prior professional work.
Tools they used
Cost: Claude Opus 5.5: from $4 in / $20 out per 1M tokens.
Set it up
Gather the documents
Collect statements, bills, invoices or tax documents for the period you want reviewed.
Ask for an audit, not actions
Have Claude Opus 5.5 list findings, amounts and suggested next steps before it does anything.
Approve each action
Approve cancellations, disputes or payments one at a time. Never give an agent open-ended access to move money.
Track the result
Record what changed and what you saved so you can check it next month. This is not financial advice.
Copy the full setup prompt
Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.
You are helping me set up this AI use case end to end in Claude Code. Goal: Have Claude Opus complete and check several tax returns What the original author did: Over a week, Opus 5.5 pushed seven tax and amended returns to completion across several people, years and states. The author, a meticulous reviewer, signed with high confidence, and Opus found errors made by earlier tax professionals. Reported result (as claimed by the author): 7 returns completed; errors found in prior professional work. Source: https://x.com/lastmjs/status/2111084344810905807 Tools they used: Claude Opus 5.5 Category: Money Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Codex. Goal: Have Claude Opus complete and check several tax returns What the original author did: Over a week, Opus 5.5 pushed seven tax and amended returns to completion across several people, years and states. The author, a meticulous reviewer, signed with high confidence, and Opus found errors made by earlier tax professionals. Reported result (as claimed by the author): 7 returns completed; errors found in prior professional work. Source: https://x.com/lastmjs/status/2111084344810905807 Tools they used: Claude Opus 5.5 Category: Money Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
You are helping me set up this AI use case end to end in Grok Bot. Goal: Have Claude Opus complete and check several tax returns What the original author did: Over a week, Opus 5.5 pushed seven tax and amended returns to completion across several people, years and states. The author, a meticulous reviewer, signed with high confidence, and Opus found errors made by earlier tax professionals. Reported result (as claimed by the author): 7 returns completed; errors found in prior professional work. Source: https://x.com/lastmjs/status/2111084344810905807 Tools they used: Claude Opus 5.5 Category: Money Please: 1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like). 2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure. 3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data. 4. Finish with a checklist to run it again next time.
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