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Sources

Every bracket, allowance, contribution, and rate on TaxMetria is sourced from a primary government authority. The list below is the canonical source registry.

Live jurisdictions

United Kingdom (England, Wales, Northern Ireland)

gb-2026-27.1

Tax year 2026 · GBP · reviewed 2026-09-16

Primary source

HMRC — Income Tax rates and Personal Allowances (current tax year 2026–27)

Fact records

  • gb-2026-basic-rate — 20% band ($0 – $37,700)
  • gb-2026-higher-rate — 40% band ($37,700 – $125,140)
  • gb-2026-additional-rate — 45% band ($125,140 – and above)
  • gb-2026-personal-allowance — exemption, GBP 12,570, applies to taxable income
  • gb-2026-ni-main-rate-band — Class 1 NI — 8% band (Primary Threshold to UEL), 8% , capped at GBP 50,270 , on income above GBP 12,570
  • gb-2026-ni-upper-rate — Class 1 NI — 2% above Upper Earnings Limit, 2% , on income above GBP 50,270

United States — Federal

us-fed-2026.1

Tax year 2026 · USD · reviewed 2026-09-16

Primary source

IRS Rev. Proc. 2025-32 — Tax Year 2026 Inflation Adjustments

Fact records

  • us-fed-2026-bracket-10 — 10% band ($0 – $12,400)
  • us-fed-2026-bracket-12 — 12% band ($12,400 – $50,400)
  • us-fed-2026-bracket-22 — 22% band ($50,400 – $105,700)
  • us-fed-2026-bracket-24 — 24% band ($105,700 – $201,775)
  • us-fed-2026-bracket-32 — 32% band ($201,775 – $256,225)
  • us-fed-2026-bracket-35 — 35% band ($256,225 – $640,600)
  • us-fed-2026-bracket-37 — 37% band ($640,600 – and above)
  • us-fed-2026-std-deduction-single — deduction, USD 16,100, applies to taxable income
  • us-fed-2026-ss-wage-base — Social Security (employee), 6.2% , capped at USD 184,500
  • us-fed-2026-medicare-rate — Medicare (employee), 1.45%
  • us-fed-2026-additional-medicare — Additional Medicare Tax, 0.9% , on income above USD 200,000

How we keep sources honest

  • Every fact record stores the direct URL to the official document, not a third-party summary.
  • When a fact is updated by a new Rev. Proc. or a new HMRC announcement, we publish a new release with a new ID and a documented diff. Old releases remain available.
  • We never cite a blog, a competitor's calculator, or an AI answer as the source for a tax rate. We may cite them to identify an issue worth investigating — but the final number comes from the authority.

See methodology for how the engine consumes these records and the corrections log for how we handle errors when found.