⚠ Hypothetical Tool - Not the Official CMS Calculator

Child Maintenance & Living Costs Calculator

The CMS currently calculates maintenance based purely on gross income - it does not consider your rent or mortgage. This calculator shows what payments might look like if your housing cost was deducted first.

Living Costs Calculator

See what you'd pay if the CMS factored in essential living costs

This is NOT the official CMS calculator. The CMS does not take living costs into account. This tool is hypothetical - it shows what maintenance might look like if living costs were deducted first. It is for informational purposes only.

Your gross salary / income

Your salary before tax - shown on your payslip as "Gross Pay".

Pension contributions (optional - salary sacrifice only)

Salary sacrifice pension reduces what the CMS counts as your income. Enter the same period as above.

Number of qualifying children

Overnight stays with paying parent

Qualifying overnight stays reduce the official CMS amount.

Monthly rent / mortgage payment

Enter your monthly housing cost - we'll deduct this before applying the CMS percentage.

What is this calculator?

This is a hypothetical tool. The official Child Maintenance Service (CMS) bases payments entirely on the paying parent's gross income. It does not take rent, mortgage, utilities, food, or any other essential costs into account.

Many paying parents feel this leaves them with too little after essential costs are paid. This calculator shows what maintenance might look like if the CMS were to deduct essential living costs first - as a basis for discussion with a solicitor.

Important Disclaimer

This calculator does not reflect actual CMS rules. The CMS will not accept a calculation based on disposable income. Do not present this figure to the CMS as your maintenance obligation. For official figures, use our main calculator or the GOV.UK service.

Does the CMS consider living costs?

Currently, no. The CMS calculation is based purely on gross income. There has been ongoing debate about whether essential costs should be factored in, but as of 2025, the official position is that they are not.

A variation can be requested for specific unusual expenses (e.g. long-distance contact travel), but general living costs are not considered.