Methodology & sources
Civic Ledger has one rule: no invented numbers. Every figure on the ledger traces to an official government document you can open yourself, down to the spreadsheet cell.
How the tax estimate works
You give three inputs: gross income, filing status, and tax year. The estimate subtracts that year's standard deduction for your filing status, then applies the ordinary marginal brackets to what remains, slice by slice. Both the deduction amounts and the bracket thresholds come from the IRS Revenue Procedure published for each tax year (the annual inflation-adjustment document), and the calculation runs entirely in your browser.
What it deliberately leaves out: tax credits, itemized deductions, capital gains rates, the Alternative Minimum Tax, self-employment tax, and state taxes. Payroll taxes for Social Security and Medicare are also separate. This keeps the estimate explainable line by line rather than pretending to be tax software.
Tax parameter sources, by year
| Year | IRS document | PDF hash (SHA-256) |
|---|---|---|
| 2018 | Revenue Procedure 2018-18 (TCJA Inflation Adjustments for Tax Year 2018), in Internal Revenue Bulletin 2018-10 Rate tables sec. 3.01 (p.11); standard deduction sec. 3.14 (p.13) | 3320a416f385… |
| 2019 | Revenue Procedure 2018-57 (Inflation Adjustments for Tax Year 2019) Rate tables sec. 3.01 (p.8); standard deduction sec. 3.16 (p.16) | 179b2103dc52… |
| 2020 | Revenue Procedure 2019-44 (Inflation Adjustments for Tax Year 2020) Rate tables sec. 3.01 (p.5); standard deduction sec. 3.16 (p.13) | 4128892f6a94… |
| 2021 | Revenue Procedure 2020-45 (Inflation Adjustments for Tax Year 2021) Rate tables sec. 3.01 (p.5); standard deduction sec. 3.16 (p.13) | 12cfb00115b8… |
| 2022 | Revenue Procedure 2021-45 (Inflation Adjustments for Tax Year 2022) Rate tables sec. 3.01 (p.5); standard deduction sec. 3.15 (p.14) | 405535647b62… |
| 2023 | Revenue Procedure 2022-38 (Inflation Adjustments for Tax Year 2023) Rate tables sec. 3.01 (p.5); standard deduction sec. 3.15 (p.13) | 6c20f8a6c9a3… |
| 2024 | Revenue Procedure 2023-34 (Inflation Adjustments for Tax Year 2024) Rate tables sec. 3.01 (p.5); standard deduction sec. 3.15 (p.12) | 544ba41c7ba6… |
| 2025 | Revenue Procedure 2024-40 (Inflation Adjustments for Tax Year 2025) Rate tables sec. 2.01 (p.5) | 4de9db6b6662… |
| 2026 | Revenue Procedure 2025-32 (Inflation Adjustments for Tax Year 2026) Rate tables sec. 4.01 (p.10); standard deduction sec. 4.14 (p.18) | e9ada115fb43… |
Where the spending numbers come from
Federal spending comes from the Historical Tables workbook published alongside the President's Budget on govinfo.gov, produced by the Office of Management and Budget (OMB). Civic Ledger reads tab hist03z1, outlays by superfunction and function, and keeps fiscal years 2018 through 2024 (the latest published actuals).
A small data pipeline downloads the workbook, records its SHA-256 file hash, and stores the tab and cell reference for every number it extracts. That is what the "View receipt" button shows: the amount, the workbook, the tab and cell it came from, and the hash of the exact file that was parsed. Category explanations carry their own citations to agency sources like the Social Security Administration and the Centers for Medicare & Medicaid Services.
"Your share" is a simple allocation: your estimated tax multiplied by each category's fraction of total outlays. The percentages include offsetting receipts, so the categories sum to the true total.
How the data stays current
A scheduled job re-runs the pipeline monthly: it checks for new budget workbooks and Revenue Procedures, refreshes the database and the committed data snapshot, and redeploys the site when something actually changed. New tax-year brackets are transcribed by hand from the IRS PDF and verified against test cases before they ship; automation fetches documents, but no number enters the ledger without a source attached. The full pipeline and data history are public in the source repository.
Frequently asked questions
- Is this my actual tax bill?
- No. It is an estimate using only the standard deduction and the ordinary marginal brackets for your filing status and year. It leaves out credits (like the Child Tax Credit), itemized deductions, capital gains rates, the Alternative Minimum Tax, and self-employment tax. For most W-2 filers who take the standard deduction it lands close; your real return can differ.
- Why doesn't it include Social Security and Medicare payroll taxes?
- Payroll taxes (FICA) are collected separately from income tax and flow through dedicated trust funds. Civic Ledger allocates only your federal income tax across total federal outlays. Adding payroll taxes is on the roadmap, clearly labeled as its own line.
- Where do the spending numbers come from?
- From the Historical Tables workbook published with the President's Budget on govinfo.gov, produced by the Office of Management and Budget (OMB). Civic Ledger parses tab hist03z1 (outlays by superfunction and function) and records the workbook's SHA-256 file hash plus the exact tab and cell each number came from.
- Why does a 2025 tax year show 2024 spending?
- Fiscal year 2024 is the most recent year with published actual outlays. When you pick a tax year newer than the latest actuals, Civic Ledger applies your tax to the most recent real spending mix instead of projections, and says so on screen.
- Why do news headlines show different numbers?
- Usually because they measure something different, not because anyone is wrong. Headlines often quote budget authority (what Congress authorizes for the future), while Civic Ledger shows outlays (what was actually spent, after the fact). Headlines may also cover a different fiscal year, or a narrower slice: for example, 'the defense budget' in the news usually means Department of Defense appropriations, while the National Defense category here also includes nuclear-weapons work at the Department of Energy and other defense activities, as the government's own accounting groups them.
- Why are these sources trustworthy?
- govinfo.gov is operated by the U.S. Government Publishing Office, the official publisher of federal documents since 1861, so what Civic Ledger downloads is the government's own record. The Historical Tables are the Office of Management and Budget's official accounting of federal spending, published with every President's Budget. IRS Revenue Procedures are the legal documents that set each year's tax brackets. Civic Ledger also records a cryptographic hash of every file it parses, so anyone can confirm the numbers came from those exact documents.
- What does 'your share' actually mean?
- Your estimated federal income tax multiplied by each category's fraction of total federal outlays. It is an allocation for understanding, not a statement that your specific dollars were routed to specific programs; money is fungible once it reaches the Treasury.