No 44 Transparency

Every number,
traceable.

Transparency is foundational to FiscalFold. Every tax figure on this platform is deterministic — computed from official statutory rates, not generated by AI.

Architecture

Deterministic by Design

Every tax figure on this platform is computed by an engine that applies official statutory bracket rates slice by slice. The math is deterministic — the same input always produces the same output. No AI, approximation, or black-box estimate is ever involved in a tax number.

Sources

Our Data Sources

United States
IRS Publication 15-T (2026) — Federal Income Tax Withholding Methods
IRS Publication 17 (2026) — Your Federal Income Tax
IRS Revenue Procedure 2025-32 — 2026 Inflation Adjustments
Spain
Agencia Tributaria — Manual Renta 2024 — Spain IRPF Tax Guide
OECD TaxBEN — Spain Country Report — Social contribution methodology
Germany
BMF Einkommensteuer Grundtabelle 2026 — German Federal Income Tax Tables
OECD TaxBEN — Germany Country Report — Social contribution methodology
United Kingdom
HMRC CWG2 (2025-26) — Rates & Thresholds for Employers
OECD TaxBEN — UK Country Report — Social contribution methodology
France
DGFiP — Brochure Pratique IR 2025 — French Income Tax Guide
OECD TaxBEN — France Country Report — Social contribution methodology
OECD Global
OECD Taxing Wages & TaxBEN — International Comparative Tax Data
Method

Calculation Methodology

01

Tax Bracket Application

Income is taxed progressively — each portion is taxed at the rate for that bracket. The effective rate is always lower than the marginal rate.

02

Standard Deductions

Each country's standard deduction or personal allowance is applied before bracket calculation. For example, the US standard deduction for 2026 is $16,100 (single).

03

Social Contributions

Employee-side social security contributions (FICA in the US, NICs in the UK, etc.) are calculated separately and shown alongside income tax for a complete picture.

Limitations

Limitations & Disclaimers

! FiscalFold provides estimates only. These are not tax filings and do not constitute tax advice.

! Regional/state/municipal taxes are not included (e.g., US state taxes, Spanish autonomous community surcharges).

! Germany uses continuous formulas, not flat brackets. Our bracket approximation may differ slightly from precise amounts.

! Only standard deductions are applied. Itemized deductions, credits, and special exemptions are not computed.

! Always consult a licensed tax professional before making financial decisions based on these calculations.

Schedule

Data Update Schedule

Last Updated
April 21, 2026
Tax Year
2026 (all countries)
Update Frequency
Annual
Source Documents
18