Child MaintenanceGuide UK
How It Works5 min read12 January 2025

What Is the CSA? (Child Support Agency Explained)

The CSA no longer exists - but millions of people still search for it. Here's what it was, what replaced it, and what you need to know now.

What does CSA stand for?

CSA stands for Child Support Agency. It was the UK government body responsible for calculating and collecting child maintenance payments from parents who lived apart from their children.

Does the CSA still exist?

No. The Child Support Agency was gradually wound down from 2012 and formally closed for new applications. It was replaced by the Child Maintenance Service (CMS), which is run by the Department for Work and Pensions (DWP).

All remaining CSA cases were closed by 2018. If you were on a CSA arrangement, you will have been moved to either a CMS case or a private arrangement.

Still say "CSA"? You're not alone. Millions of people still search "CSA calculator" and "how does the CSA work" - but the correct term is now the CMS. Everything on this site refers to the CMS, which works in the same way but has updated rates and rules.

How was CSA maintenance calculated?

The old CSA used a similar gross-income-based formula to the CMS today. The CMS has largely carried forward the same approach but with updated procedures and enforcement powers.

What replaced the CSA?

The Child Maintenance Service (CMS) replaced the CSA. The CMS operates in the same way - it uses HMRC income data to calculate payments, and can collect and enforce payments if needed. You can read more in our guide: What is the Child Maintenance Service?

How to contact the CMS (formerly CSA)

You can contact the CMS on 0800 171 2345 (free from landlines and mobiles, Monday–Friday 8am–6pm). You can also apply and manage your case online at GOV.UK.

💡 Tip: CMS agents vary widely in quality. If you receive incorrect or unhelpful advice — hang up and call back. A different agent can make all the difference. Always note the date, time, and name of the person you spoke to.

Can I use a CSA calculator?

You can use our child maintenance calculator to estimate your payments. Unlike the official calculator, ours is based on your net (take-home) pay, not your gross income - which makes it much easier to use.

Frequently Asked Questions

When did the CSA close?
The CSA stopped accepting new applications in 2012 when the CMS launched. All remaining CSA cases were closed by 2018.
I have CSA arrears - do they still apply?
Yes. Arrears built up under the old CSA system were transferred to the CMS. Outstanding CSA arrears can still be pursued and enforced.
Is the CMS the same as the CSA?
They do the same job, but they are different organisations. The CMS replaced the CSA and has updated rules, rates, and enforcement powers.

Want to know exactly what you'd pay?

Use our free net pay calculator - enter your take-home pay, not gross, for a realistic figure.

Try the Calculator →
Disclaimer: This article provides general information only and is not legal or financial advice. Rules and rates can change - always verify with the official UK government website or seek professional advice.