API Changelog

Phase 1 auth system deployed

Scoped API keys now live. Keys follow the ctc_[32 hex] format. Tier-based endpoint access, monthly rate limiting, and per-minute burst protection are active. All authenticated responses include X-RateLimit-* headers.

• Free tier: 1,000 req/month, hard cap
• Paid tiers: overage tracked for end-of-month billing
• Burst limiter: 60-second sliding window per API key

Germany — 2026 rates verified

All Germany rates confirmed against Bundeszentralamt für Steuern 2026 guidance.

• Grundfreibetrag (personal allowance): €12,348
• Solidarity surcharge (Solidaritätszuschlag): 5.5% on income tax above threshold — applies at higher incomes
• Social security contribution ceilings confirmed (west/east split)
• accuracy_confidence remains 0.95

Spain — 2026 rates verified

Spain rates audited against Agencia Tributaria 2026 tables.

• Social security (Seguridad Social) contribution ceiling: updated from €58,914 to €61,214/year
• Solidarity tax thresholds (high earners) confirmed

New Zealand — 2026 rates verified

New Zealand rates audited against Inland Revenue (IR) 2026 guidance.

• ACC earners' levy rate: updated from 1.39% to 1.75%
• KiwiSaver employee contribution: updated from 3.0% to 3.5%

OpenAPI spec updated (v1.1)

Spec improvements — no breaking changes:

• Added x-access-tier extension to every endpoint
• Added reusable 401/403/429 response components
• Clarified jurisdiction disambiguation (CA = California when country is US)
• Added /compare latency note (2–5s for 20-country requests)
• Documented accuracy_confidence values (0.95 vs 0.70)
• Added versioning policy (v1 supported 12 months after any v2 announcement)
• Added X-RateLimit-* header documentation

Australia — FY2026 rates verified

Australia rates updated for the 2025–26 tax year (ending 30 June 2026) against ATO guidance.

• Stage 3 tax cuts reflected in all brackets
• Medicare levy: 2.0% confirmed
• Super guarantee rate: 11.5% confirmed

Two-provider FX conversion launched

Currency conversion now uses Frankfurter (ECB) as primary with exchangerate-api.com as fallback for 160+ currencies. The fx_source field in responses indicates which provider was used.

United Kingdom — 2026/27 rates

UK rates updated for the 2026/27 tax year (from 6 April 2026) against HMRC guidance.

• Personal allowance: £12,570 (unchanged)
• NI contribution thresholds updated
• Scotland: higher rate threshold confirmed

GET /countries/{code}/rates endpoint added

New endpoint returning raw tax brackets, deductions, and social contribution rates without requiring an income calculation. Responses are cached for 1 hour. Available on Starter tier and above.

United States — 2026 IRS brackets

US federal tax brackets and standard deductions updated for tax year 2026 following IRS inflation adjustments.

• Standard deduction (single): updated
• Standard deduction (married filing jointly): updated
• FICA Social Security wage base: updated
• All 50 states + DC bracket data reviewed

API v1 launched

CountryTaxCalc API v1 launched at api.countrytaxcalc.com. Covers 111 countries including all 50 US states and 13 Canadian provinces. OpenAPI 3.0.3 spec available.