Claude Code · Anthropic
Compute a small company's tax return and have a second agent audit it
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.
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.
How it went
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.
Worth knowing
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 Claude Code
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.
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Someone using it at work posted about it. Any numbers are theirs, so we write "the poster says".
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