Our Methodology

Data Sources

All data on PlainTaxData comes directly from official Internal Revenue Service (IRS.gov) sources. We reference the following IRS publications and announcements for each tax parameter:

• Tax brackets: IRS Revenue Procedures (annual inflation adjustments, e.g., Rev. Proc. 2024-61).
• Standard deductions: IRS Publication 501 – Dependents, Standard Deduction, and Filing Information.
• Capital gains rates: IRS Publication 550 – Investment Income and Expenses.
• Retirement contribution limits: IRS annual announcements (IR-2024-285 and similar IR notices).
• Tax credits (EITC, CTC, CDCTC): IRS Publications 596, 972, and 503.
• Alternative Minimum Tax: IRS Form 6251 instructions and associated revenue procedures.
• IRS Statistics of Income (SOI): SOI Individual Statistical Tables – effective tax rate analysis by income percentile.

How We Present the Data

We extract tax parameters from IRS publications each tax year and store them in a structured format. For each filing status and year, we record:

• Marginal tax bracket thresholds and rates for ordinary income.
• Long-term capital gains rate thresholds (0%, 15%, 20%).
• Standard deduction amounts by filing status and age.
• Retirement account contribution limits (401k, IRA, Roth IRA, HSA, FSA).
• EITC income thresholds and maximum credit amounts by number of qualifying children.
• Child Tax Credit phase-in and phase-out ranges.
• AMT exemption amounts and phase-out thresholds.

Tax Estimator Methodology

The interactive tax estimator computes estimated federal income tax liability using the following approach:

• Adjusted Gross Income (AGI) = gross income minus above-the-line deductions you specify.
• Taxable income = AGI minus the greater of standard deduction or itemized deductions entered.
• Tax computed by applying each bracket's marginal rate to the income within that bracket.
• Credits (EITC, CTC) applied to reduce tax liability.
• Capital gains taxed separately at long-term rates where applicable.

This is a simplified estimate. It does not account for state taxes, self-employment tax, the Net Investment Income Tax (NIIT), AMT, phase-outs of certain deductions, or every credit and deduction scenario. Use it for rough planning, not as a substitute for tax software or a tax professional.

Corpus placement (#N of M)

Every federal tax-year bracket page states where that year sits in PlainTaxData's own published-year corpus. Placement is computed from the same IRS Revenue Procedure tables the detail pages render - never hand-picked and never invented as a quality score.

• Single standard deduction - rank among all published tax years by the Single standard deduction dollar amount, highest first. Later inflation-adjusted years sit near #1; this measures the non-itemizer floor IRS published for that year, not a judgment that a higher deduction is always better for every household.
• YoY 37% threshold inflation lift - rank among year-over-year pairs that have a prior published year, by the percent increase in the Single 37% bracket start versus the prior year, largest lift first. Absolute deduction size and YoY inflation adjustment often diverge (a recent year can lead on deduction dollars while ranking mid-pack on that year's inflation jump).

The Callout on each tax-year bracket page names the applicable signals and links here so the derivation stays visible.

Accuracy and Updates

The IRS adjusts many tax parameters annually for inflation. We update our compiled figures each year when the IRS publishes its annual revenue procedure for inflation adjustments, typically in October or November. While we strive for accuracy, tax law changes frequently, always verify figures against current IRS publications before making tax decisions.

Processing Pipeline

We build the PlainTaxData dataset through a structured extraction and validation process:

• Download IRS Revenue Procedures, publications, and IR announcements for each tax year as they are released
• Extract tax bracket thresholds, standard deductions, credit amounts, and contribution limits from the official IRS text
• Validate extracted figures by cross-referencing multiple IRS sources (Revenue Procedures vs. Publications vs. Form instructions)
• Store each parameter with its tax year, filing status, and source IRS document reference for traceability
• Build the interactive tax estimator's calculation engine from the validated parameter set

No tax data is fabricated or interpolated. Every figure comes directly from an official IRS publication or announcement. Where the IRS has not yet published a figure for a given tax year, we do not estimate or project it.

Important Disclaimer

PlainTaxData is an informational resource only. It does not constitute tax, legal, or financial advice. Tax situations are individual, consult a qualified tax professional (CPA, EA, or tax attorney) for advice specific to your circumstances.

Not Affiliated

PlainTaxData is not affiliated with the Internal Revenue Service or any government agency. We are an independent data portal presenting official IRS-published tax reference data in a more accessible format.