Year-End Books Cleanup Skill: Schedule C Categorizer & 1099-NEC Payee List

Clean up a year of business bank and card exports with your own AI agent, and hand your accountant a tidy report.

This agent skill uses the open Agent Skills (SKILL.md) format and is built for Claude Code, Cursor and Codex. A bundled Python script does all the math, so the same files always give the same numbers. Your agent runs it and walks you through anything uncertain.

WHAT IT DOES

• Reads messy CSV exports: signed or Debit/Credit columns, bank preamble lines, (12.00) and 12.00 CR amounts, several date formats
• Removes duplicate rows from overlapping downloads
• Sorts transactions into suggested Schedule C lines (1, 2, 6, 8–27b), with a confidence level for each row and a review list for the uncertain ones
• Sets aside transfers, credit-card payments, owner draws, personal spending, tax and loan payments
• Handles refunds and split business use (e.g. a phone that's 60% business)
• Lists possible Form 1099-NEC payees using the $2,000 threshold for payments made in 2026, separates card, PayPal-type and platform payments (generally reported on Form 1099-K), and notes that 2026 forms are due Monday, February 1, 2027
• Flags large purchases as possible capital assets for your CPA
• Writes a CPA-ready report (HTML and Markdown) plus summary CSVs, with a reconciliation check and questions for your tax professional

WHAT'S IN THE DOWNLOAD

• The skill folder: SKILL.md, the Python script, an editable rules file, 5 reference guides and 20 automated tests
• Fictional demo data (4 sample CSVs) and a sample report, so you can try it before using your own files
• INSTALL.md with folder locations for Claude Code, Cursor and Codex

REQUIREMENTS

• An AI agent that supports Agent Skills and can run local commands (your own account with that tool)
• Python 3.8 or newer. Standard library only, nothing to install.
• CSV exports with a date, a description, and an amount (or Debit/Credit) column

WHO IT'S FOR

Freelancers, sole proprietors and single-member LLC owners who file Schedule C. Not for payroll, inventory/COGS, depreciation schedules, mileage, home office, partnerships, corporations, state returns or non-US formats.

NOT TAX ADVICE

This skill organizes your own transaction data to help you prepare for your accountant or tax software. It is not tax, legal, or accounting advice, it does not file anything, and its categories are suggestions that can be wrong. Review every line yourself, and have a qualified tax professional (CPA, EA, or similar) check anything you file. Whether someone needs a 1099 depends on facts the skill cannot see, such as how you paid them and their entity type.

AI-ASSISTED

This skill was built with AI assistance. Its script passes 20 automated tests on fictional demo data (Python 3.8 and 3.13, Linux). When you run it, your own AI agent handles the conversation and can make mistakes, so check the output.

YOUR DATA

The script runs on your computer, makes no network calls, and reads only the files you give it. Your agent sees the CSV contents under your agent/model provider's terms.

License: use in your own business(es) or the businesses you keep books for; no resale or redistribution.

Questions: quietenginecompany@gmail.com