Our Methodology & Data Sources
Every number on this site is traceable to an official source. Here's exactly how we collect, verify, and maintain the data behind our calculators.
Our Guiding Principles
Official Sources First
We source data exclusively from government tax authorities, immigration portals, central banks, and established international organizations. Third-party sources are only used when official data is unavailable, and are always cross-referenced.
Transparency Over Simplicity
We show our work. Every calculator page explains which data sources were used, when they were last updated, and what assumptions the model makes. We'd rather present a nuanced answer with caveats than an oversimplified number.
Conservative Estimates
When ranges exist (e.g., visa processing fees vary by consulate), we default to the higher end. We'd rather have users pleasantly surprised by lower costs than caught short by unexpected expenses.
Data Sources by Tool
Each calculator draws from specific, authoritative data sources. Below is a detailed breakdown:
Salary After Tax Calculator
- National tax authority publications (IRS, HMRC, ATO, CRA, and 36 more) for income tax brackets and personal allowances
- Official social security / national insurance rate schedules published by each country's social welfare authority
- KPMG, Deloitte, and PwC annual country tax guides for cross-verification of rates
Update frequency: Annually (January), when countries publish new tax year brackets. Spot-checked quarterly against professional tax guides.
Cost of Living (Country & City)
- Numbeo cost-of-living database — the world's largest crowd-sourced collection of city-level prices (rent, groceries, restaurants, transit, utilities)
- OECD Purchasing Power Parity (PPP) rates for country-level comparisons
- Government statistical agencies for consumer price indices and rental market reports
Update frequency: Semi-annually (Numbeo updates mid-year and year-end). PPP rates updated annually from OECD data.
Currency Converter
- European Central Bank (ECB) reference rates via the Frankfurter API — mid-market rates published daily at 16:00 CET
- 55 central bank exchange rate feeds aggregated for comprehensive currency coverage
- Manual pegged rates for currencies with fixed or managed exchange rate regimes (AED, SAR, ARS, CLP, COP, VND)
Update frequency: Daily automated update at 7:00 AM UTC via scheduled task. Rates reflect the previous business day's ECB fixing.
Salary Comparison Tool
- Same tax bracket data as the Salary Calculator (national tax authorities, verified against KPMG/Deloitte/PwC)
- Daily exchange rates from the Currency Converter for cross-country salary conversion
- Purchasing Power Parity adjustments from OECD for real-value comparisons
Update frequency: Tax brackets updated annually; exchange rates updated daily; PPP rates updated annually.
Visa Financial Requirements
- Official immigration authority websites (UKVI, USCIS, IRCC, DHA Australia, IND Netherlands, etc.) for financial thresholds and documentation requirements
- Embassy and consulate published fee schedules for visa processing costs
- Official government fee calculators where available (e.g., UK Points-Based System calculator)
Update frequency: Reviewed quarterly and updated within days of official policy changes.
Our Verification Process
Raw data is never published directly. Every data point passes through a multi-stage verification pipeline:
- 1
Collection
Data is gathered from the primary authoritative source (government websites, central banks, official APIs). We record the source URL, access date, and specific page/section for full traceability.
- 2
Cross-Verification
Critical data points (tax brackets, visa thresholds) are cross-checked against at least one secondary source — typically a 'Big Four' accounting firm country guide (KPMG, Deloitte, PwC, EY) or an established financial comparison platform.
- 3
Calculation Validation
Calculator outputs are tested against known scenarios: official tax authority examples, published visa requirement checklists, and verified real-world cases from immigration forums and professional tax advisors.
- 4
Edge Case Testing
We test boundary conditions — zero income, very high income, minimum wage scenarios, and unusual situations like split-year residency or multiple visa types — to ensure calculations remain accurate across all inputs.
- 5
Peer Review
Before publishing updates, changes are reviewed for mathematical accuracy, consistency with existing data, and compliance with the current regulatory landscape.
Update Cadence & Automation
| Data Category | Frequency | Method |
|---|---|---|
| Exchange rates | Daily | Automated (Frankfurter API → rebuild) |
| Tax brackets & rates | Annually (January) | Manual review of government publications |
| Cost-of-living indices | Semi-annually | Manual transcription from Numbeo rankings |
| City-level prices | Semi-annually | Manual transcription from Numbeo city data |
| Visa financial thresholds | Quarterly | Manual review of immigration portals |
| Payment platform fees | Quarterly | Manual audit of published fee schedules |
Exchange rates are the only data category updated automatically. All other data categories require manual review because they depend on government publications, policy changes, and data sources without free APIs. We prioritize accuracy over automation — a wrong automated update is worse than a slightly delayed manual one.
Known Limitations & Disclaimers
No financial calculator can capture every nuance of real-world regulations. We believe transparency about our limitations is as important as the accuracy of our calculations:
Regional/State Taxes Not Included
Our salary calculators show national/federal taxes only. Countries like the USA, Canada, Switzerland, and Germany have significant state/provincial/cantonal taxes that can add 3–15%+ to your effective rate. We clearly note this on each calculator page.
Individual Circumstances Vary
Tax credits, deductions, family status, disability allowances, and employer-specific benefits can significantly change your actual tax liability. Our calculators model the standard employee scenario without itemized deductions.
Exchange Rate Timing
Our daily exchange rates reflect the ECB's previous business day fixing at 16:00 CET. Actual rates at the moment of your transaction may differ by 0.1–0.5% due to intraday volatility.
Cost of Living Sampling
Numbeo data is crowd-sourced, meaning it reflects prices reported by contributors rather than official government statistics. While Numbeo's dataset is the largest of its kind and generally reliable, individual prices may not match your specific experience.
Not Professional Advice
Our tools provide estimates for planning purposes. For binding tax returns, visa applications, or major financial decisions, always consult a qualified tax professional, immigration attorney, or certified financial planner who can evaluate your complete situation.
Found an Error?
Accuracy is our top priority. If you notice a discrepancy between our calculations and official requirements, please let us know. User reports are one of our most valuable quality assurance channels.
Report a Data Issue