Unearned / additional income
Ask CMS to include income streams outside the standard HMRC earned-income feed.
Variations and income disputes
The standard CMS formula uses gross earned income from HMRC (and benefits status). A variation asks CMS to take account of extra income, assets, or special expenses that the basic formula misses. Either parent can apply.
This page is orientation only. Confirm current rules on GOV.UK and seek advice for complex income.
When a variation may help
- You believe the other parent has unearned income (for example rent, dividends) not in the HMRC earned figure.
- Assets or diverted income should be considered.
- You have special expenses (contact costs, illness/disability costs, prior debts) that should reduce liability.
- Your own income figure is wrong for a different reason — that is usually a calculation challenge or change of circumstances, not always a “variation”.
Common variation themes
Assets
In some cases assets can affect the calculation. Evidence must be specific and current.
Special expenses
Documented costs that the rules allow to reduce the amount — keep receipts and a clear schedule.
Wrong HMRC figure
If the tax year or gross figure is simply wrong, request a breakdown and use mandatory reconsideration with payslips/P60 evidence.
Evidence to prepare
- Bank statements and tax documents for the disputed income period
- Company accounts / dividend vouchers if relevant
- Tenancy or rental schedules for property income
- Receipts and mileage logs for special expenses
- A one-page chronology of what CMS currently uses vs what you say is missing
See also Evidence standards.
How to apply and escalate
- Ask CMS in writing for a variation (or report the income issue) and keep the date.
- If CMS refuse or ignore you, use the dispute route (explanation → MR → tribunal).
- Use the letter builder’s change-of-circumstances / variation grounds checklist.
Related
- Indicative calculator (does not model variations)
- Methodology — known gaps
- Findings — complex earnings and opacity