Child Maintenance Calculator

Child maintenance is calculated using the CMS (Child Maintenance Service) formula based on the paying parent gross weekly income, the number of children, and how many overnight stays the children have with each parent.

Enter your details and this calculator will estimate your weekly child maintenance figure using the current CMS formula for 2025/2026. If you have any comments or would like additional tools, please leave a comment at the bottom of this page.

← See All 12 Free Guidance Tools

Gross annual income (before tax)

Your total yearly income before tax and National Insurance. If you're not sure, check your payslip or P60.

Please enter your gross annual income

Number of children to pay maintenance for

Please select the number of children

Number of other children living with you

Children from another relationship who live in your household.

Number of overnight stays per year

How many nights per year do the children you pay for stay overnight with you?

Your privacy is protected. We do not store any personal information. This calculation happens entirely in your browser.

Your Estimated Child Maintenance

Per Week

Per Month

Per Year

Preparing your explanation...

This usually takes a few seconds

Your Rights and Options

This calculator provides an estimate only based on the standard CMS formula. Your actual liability may differ depending on your circumstances. For accurate figures, contact the Child Maintenance Service on 0800 171 2171 or visit gov.uk. This tool does not constitute financial or legal advice.

2 Comments

Add Your Comment

SeparatedDads Editor 04/06/2026 at 10:03 am

@JohnNanny Working it out by hand is a nightmare, so it makes sense the calculator gave you a clearer picture. Just remember the figure is a guide based on the standard CMS formula, and the real amount can shift with things like shared care nights or a change in income. If your circumstances change, rerun it so your payments stay accurate. Keeping a record of what you pay is always worth doing too.

JohnNanny 02/04/2026 at 6:14 am

I struggled working this out manually but this helped me understand how much i need to pay. THanks

Ask Separated Dads a question

Ask our editorial team a question and we will reply with our advice. Tell us as much about your situation as you can: the more detail you give, the more useful our answer can be.

You do not need to use your real name. Please do not include your full address, phone number, email address, or the names of other people. We may edit or remove identifying details for privacy and legal reasons.

Comments are moderated before publication.