UK Critical Illness Cover Calculator — Methodology

Last verified 5 May 2026 against ABI Statement of Best Practice for Critical Illness Cover. Calculator at /uk/insurance/critical-illness-calculator/.

What this calculator does

Estimates the lump-sum critical illness cover needed to fund recovery, replace income for a defined recovery period, and meet additional treatment, mobility, or home-adaptation costs.

The formula

needs = (monthlyIncomeToReplace × 12 × recoveryYears)
      + treatmentAndMobilityCosts
      + homeAdaptationCosts
      + childcareTopUp
      + outstandingShortTermDebts

resources = sickPayLumpSum
          + employerCriticalIllnessCover
          + emergencySavings

recommendedSumAssured = max(0, needs - resources)

Authoritative sources

• ABI Statement of Best Practice for Critical Illness Cover
• MoneyHelper — critical illness cover
• FCA — protection insurance guidance

Assumptions and limitations

• Recovery period default is 2 years; users with longer-term conditions should consider income protection in parallel.
• Does not model the full ABI condition list — assumes the user buys cover meeting the ABI Statement of Best Practice minimums.
• Does not assess premium affordability or insurer-specific definitions (severity-based payouts, partial payments).
• Children's critical illness cover, if included on the policy, is treated as bundled and not sized separately.

Source data

This calculator is rate-free — it does not depend on a tax-year rate table. The methodology and assumptions above are the source of truth.

Verification log

• 5 May 2026: Sizing methodology reviewed against ABI Statement of Best Practice; rate-free calculation