Tax Rules Overwhelmed Me, So I Turned Them Into a Checklist

The First Time I Filed US Taxes, Dozens of Pages of Rules Beat Me

At 10 p.m. last Tuesday, I sat at my dining table in a San Francisco apartment, checking quarterly estimated taxes. The form held only a few lines of numbers, but behind them was a chain of conditions: different income types, different rules for operating across states, and prerequisites for every deduction. That night, I searched a PDF for keywords and grew less confident with every page.

I am not an accountant or a programmer, and that kind of document—where every sentence seems to carry an exception—is exactly what gets me stuck. What I later learned was that formal methods like Lean exist to turn complex rules into small, step-by-step questions we can check.

It Works by Rewriting Tax Law as Verifiable Rules

In plain terms, formalization does not mean adding another piece of software. It means breaking legal provisions into rules of the form, “If A is satisfied, then B follows,” then using a computer to check whether those rules conflict, leave gaps, or produce calculation errors.

Lexifina’s article uses US tax law to demonstrate the approach. Sarah, one of the participants, works at a consulting studio in New York. She encoded the sales-tax provisions for interstate transactions rule by rule; each time she added one, she ran the checker to verify that the full ruleset remained consistent.

For a freelancer, this will not file our taxes. It does turn “Did I miss something?” into a much clearer checklist.

Replicating It Today: Start Small with Free Tools

Money: Lean itself is free, and a small pilot should cost $0. Getting help organizing the provisions might run from $500 to $3,000.

Time: Expect 2–4 hours to learn the concepts and about 1–2 weeks to organize the rules for one topic.

Technical barrier: No programming is required, but we need to be willing to break natural-language provisions into individual statements. The first time we handle a cross-reference, it is easy to get confused.

First step: Open Lean’s online editor, create a file, and write just one rule we encounter often—for example, “How to calculate tax after reaching a certain income threshold.” Then click “Check” on the page.

Whether It Fits Depends on How Complex Our Business Is

If we are just starting out and our income structure is simple, this tool is not essential. Accounting software plus human advice is safer for now. Once we have one or two US clients and state-level tax differences begin showing up, I would pilot one topic rather than rush to cover the entire tax code.

A shared ruleset becomes more worthwhile when we are scaling and several people in the team handle rules for different regions. I also made a mistake at this stage: I tried to enter the entire tax code at once, and the maintenance cost scared me off. Not trying it is fine too. When the same concrete problem keeps coming up, we can formalize that one rule and leave the rest for later.