How our UK Cost Index is compiled

Phase 1 — Until Q3 2026

While we build our own primary data pipeline, the Cost Index draws on two authoritative published UK sources:

• ABI Motor Insurance Premium Tracker — a 28-million-policy dataset published quarterly. National-average figures (e.g. £604 35yo male, £560 all comprehensive Q1 2026) come from here.
• Confused.com Car Insurance Price Index (powered by WTW) — built from more than 6 million quotes each quarter. It measures the average premium quoted to shoppers (£719, Mar–May 2026), which is a different measure from the ABI's average premium paid (£560). We never compare the two as though they were equivalent; where this site publishes a single blended "~£600" planning figure, it is explicitly a blend of both bases and is labelled as such.

Age-banded and regional figures combine ABI national averages with the published age-band averages in the Confused.com Car Insurance Price Index, MoneyHelper and broker-published age-band data. Cross-validation across three sources before publication. Age-band figures on this site are quoted-premium averages and are labelled on that basis.

Phase 2 — From Q3 2026

The index transitions to primary network data: quote requests originating through carinsuranceexpert.co.uk. Outliers above the 99th percentile are excluded. Comprehensive cover only; private use; all vehicles unless otherwise specified.

Sampling rules

• Comprehensive cover only — third-party and TPFT excluded
• Private use — taxi, courier, business-use heavy excluded
• Standard mileage — figures assume 8,000–12,000 annual miles
• UK postcodes — England, Scotland, Wales; Northern Ireland excluded (different market structure)

Refresh cadence

Quarterly — every February, May, August and November. The dateModified field on each page reflects the most recent refresh. Major regulatory changes trigger out-of-cycle updates as needed.

Citation

Our datasets are available under CC BY 4.0 for editorial citation with attribution: "Car Insurance Expert UK Cost Index, [period]". Bespoke breakdowns and custom dataset extracts: editorial@carinsuranceexpert.co.uk.

Confidence intervals

Where we publish a single figure (e.g. "average premium for 17-year-olds is £1,695" — Confused.com Car Insurance Price Index, Mar–May 2026), it is the published average from the named source on that source's own basis, not our own modelled estimate. Where we publish ranges (e.g. £604–£842), these reflect the actual range of typical quotes for the cohort.

Last updated: 5 August 2026