An S-Corp owner who had used a CPA for decades prepared this year's business return himself: Claude Code wrote scripts to compute the forms from QuickBooks and bank exports, and Codex reviewed them until both agreed.
- First reported
- common-sense.com · 15 Feb 2026
- Added
- 13 Oct 2026
- Source checked
- 13 Oct 2026
What they did
He put QuickBooks and bank exports in a private Git repository. Claude Code wrote Python scripts that parse the data and compute the corporate return, the balance sheet schedule and the shareholder K-1. Codex then reviewed the scripts in several rounds, tracing figures from source data to output, while he made the decisions.
What happened
The poster says Codex raised three findings, the most serious being a balance sheet line computed from total liabilities instead of other current liabilities. The process also surfaced bookkeeping mistakes he had made during the year.
Keep in mind
The post does not say whether the return was filed or whether a CPA reviewed it. It is one owner's account, not tax guidance.
Try it with your agent
In this repository, <your accounting export folder> holds my year-end trial balance and bank exports. Write Python that maps each account to the lines of <your company tax form and schedules>, prints every figure with the accounts it came from, and writes the results to a CSV. Keep the mapping in a separate file I can review. Afterwards I will ask another agent to audit the mapping, so comment every assumption.
Replace the <angle brackets> with your own details.
Original source
common-sense.comUser storySomeone who uses the agent described their own setup. Figures are theirs.
Tools for this kind of work
- RepoConnect your agent to Stripe billing, payments and docs
- RepoWork with QuickBooks Online records and financial reports
