Methodology

This page explains how CMS Help tools work and where they are limited.

How the estimator works

Starts from gross weekly income entered by the user (optional benefits checkbox).
Applies reduction for other children in the paying parent’s household (11% / 14% / 16%).
Selects a CMS rate band: nil, flat (£7), reduced, basic, or basic-plus (income above £800).
Applies shared care reductions for reduced/basic bands (52+ nights), with a £7 floor where rules require it.
Outputs the band used, adjusted income, and indicative weekly/yearly amounts.

Rate bands summarised from GOV.UK: How child maintenance is worked out (last checked August 2026).

Single paying parent and one active case context.
Stable income profile (no advanced handling for fluctuating self-employment or one-off spikes).
No variation decision (unearned income, assets, special expenses) unless the user models it manually.
Pension contributions are not deducted unless the user reduces the income figure first.
Default rates (where income is unknown) are not modelled.
Collection fees are treated separately from core liability — see Findings.

Templates follow the GOV.UK / Citizens Advice CMS pathway: explanation → MR → tribunal, and separately complaint → review → ICE.
Deep links: index.html?letter=mr#letters (and other type codes) pre-select the letter type.
Exports use Word-compatible .doc and browser PDF/print for formal packs.
When signed in, drafts can save privately to My Case.
Drafts are guidance only — deadlines and wording should be checked against your CMS letters.

Compares expected liability (weekly × weeks) with total paid and CMS claimed arrears.
Optional payment ledger lines can fill the total-paid field and appear on the Excel export.
Variance is indicative — always request CMS’s own line-by-line ledger.

Prefer primary records: CMS letters, statements, bank evidence, court documents.
Log dates and references for every event.
Separate proven facts from assumptions.
Redact identifying child and third-party details before sharing documents.

See the full checklist in Guides → Evidence.