Methodology
CouncilData exists because nobody aggregates what councils are legally required to publish — and most who try get it wrong. Accuracy is the entire brand, so the rules below are non-negotiable.
The five rules
1. No record without a source URL. Every figure links to the council's own page or document — never a third-party aggregator. If the council doesn't publish it, we don't publish it.
2. No record without a verified date. Every page shows when the figure was last read from source. Stale records degrade visibly, never silently.
3. Two-pass verification. An extraction pass and an independent re-check against the same source. If they disagree, the record is quarantined — not published.
4. Arithmetic checks. Council tax bands are fixed fractions of Band D (the ninths). Every table must reconcile to the statutory ratios to the penny. This is how we catch typos on councils' own pages.
5. Append-only changelog. When a figure changes, we record old value, new value, date noticed and source. Corrections are public.
Current coverage
Council tax 2026/27: 350 of 350 UK billing authorities recorded, 339 two-pass verified. The remaining records are marked “awaiting verification” on their pages and excluded from rankings — we'd rather show a gap than a guess. Browse the result on the national table.
What we've caught
Verification isn't theatre — first-pass collection found aggregators quoting Cardiff and Newcastle materially wrong, a viral false claim about Coventry, and errors on councils' own pages (Westminster, Islington, Exeter). The full write-up is here.
Reusing the data
Headline tables are free under CC BY 4.0 with attribution to CouncilData and a link. Bulk data, full history and change alerts are available commercially — see downloads & licensing.