Sources

Every authoritative dataset feeding infoz.com calculators and content, organized by category. Each entry links directly to the primary publication and shows the date a human reviewer last verified its contents.

Site-wide last-checked: 2026-04-27. Per-page sources are also listed in the Sources block on each calculator page.

Tax

IRS Revenue Procedure 2025-32 (2026 inflation adjustments)
2026 federal income-tax brackets, standard deduction, AMT exemption, child tax credit, retirement contribution limits.
Jurisdiction: United States · Last checked 2026-04-27
IRS — Tax Withholding Estimator
Reference behavior for the gross-to-net paycheck calculator.
Jurisdiction: United States · Last checked 2026-04-27
HMRC — Income Tax rates and Personal Allowances
England/Wales/NI bands, Personal Allowance, £100k taper.
Jurisdiction: United Kingdom · Last checked 2026-04-27
Scottish Government — Income Tax in Scotland
Scotland-specific six-band schedule on non-savings, non-dividend income.
Jurisdiction: United Kingdom — Scotland · Last checked 2026-04-27
ATO — Individual income tax rates
Resident bracket schedule. Reflects the post-Stage-3 cuts effective 1 July 2024.
Jurisdiction: Australia · Last checked 2026-04-27
IRAS — Tax Residency and Tax Rates
Resident progressive 13-band schedule (0% to 24%) for YA 2026.
Jurisdiction: Singapore · Last checked 2026-04-27
CRA — Canadian income tax rates for individuals
Federal income-tax brackets and the Basic Personal Amount.
Jurisdiction: Canada · Last checked 2026-04-27

Payroll

SSA — Contribution and Benefit Base
Annual Social Security wage base ($176,100 for 2026 placeholder).
Jurisdiction: United States · Last checked 2026-04-27
HMRC — National Insurance rates and categories
Class 1 employee thresholds and rates (8% main / 2% upper).
Jurisdiction: United Kingdom · Last checked 2026-04-27

Tax (legislation)

One, Big, Beautiful Bill Act (Public Law 119-21, July 4, 2025)
Source for the $6,000 senior bonus deduction (2025–2028).
Jurisdiction: United States · Last checked 2026-04-27

Education / Loans

GOV.UK — Repaying your student loan: what you pay
Plan 1 / 2 / 4 / 5 / Postgraduate thresholds and rates.
Jurisdiction: United Kingdom · Last checked 2026-04-27

Healthcare levy

ATO — Medicare levy
2% Medicare Levy on taxable income.
Jurisdiction: Australia · Last checked 2026-04-27

Investing

SEC — Compound Interest Calculator
Reference for the annuity-immediate convention used in our compound interest tool.
Jurisdiction: United States · Last checked 2026-04-27

Investing — research

Cooley, Hubbard & Walz — Trinity Study (1998 + 2011 update)
Origin of the 4% safe-withdrawal-rate heuristic used in the FIRE calculator.
Jurisdiction: United States · Last checked 2026-04-27

Mortgages

Consumer Financial Protection Bureau — Owning a Home
Reference for mortgage education and lender disclosures.
Jurisdiction: United States · Last checked 2026-04-27

Mortgages — statute

Homeowners Protection Act of 1998 (12 U.S.C. § 4901 et seq.)
Federal statute for automatic PMI termination at 78% LTV.
Jurisdiction: United States · Last checked 2026-04-27

Self-employment

IRS — Schedule SE (Form 1040), Self-Employment Tax
92.35% adjustment, 12.4% SS + 2.9% Medicare, half-SE deduction.
Jurisdiction: United States · Last checked 2026-04-27

Cost of living

Numbeo — Cost of Living Index
Reference for COL index inputs in the salary negotiation calculator.
Jurisdiction: International · Last checked 2026-04-27

PPP

OECD — Purchasing Power Parities
OECD PPP statistics for cross-country comparison context.
Jurisdiction: International · Last checked 2026-04-27

Currency

exchangerate.host — Daily FX rates (ECB-sourced)
Free, ECB-sourced daily reference rates used as the FX default for cross-border tools.
Jurisdiction: International · Last checked 2026-04-27