Comparison Guide · 2026-07-10
Child Maintenance Service vs Private Arrangement UK 2026
Separated parents can either apply to the government-run Child Maintenance Service (CMS), which calculates and can collect child maintenance using a statutory formula, or agree a private, family-based arrangement between themselves with no formal calculation or government involvement. The CMS offers a fixed, enforceable formula backed by real powers of collection, while a private arrangement offers flexibility and no fees, but depends entirely on both parents keeping their word.
At a Glance
| Feature | Child Maintenance Service | Private Arrangement |
|---|---|---|
| How the amount is set | Statutory formula based on gross income, children and overnight stays | Whatever both parents agree between themselves |
| Set-up cost | £20 application fee (some exemptions apply) | None |
| Ongoing fees | Collect and Pay service: 20% extra on payer, 4% deducted from receiver | None |
| Enforceable by government? | Yes — wage deductions, bank orders, court action | No — relies on mutual trust |
| Flexibility | Fixed formula, limited variation grounds | Fully flexible (can include school fees, extras) |
| Speed to arrange | Takes weeks to process an application and calculation | Can start immediately by agreement |
| Best for | Where trust has broken down or payments are missed | Amicable separations with reliable payment history |
When the CMS Is the Better Route
- A private arrangement has broken down or the paying parent is unreliable
- You need real enforcement powers, such as deductions direct from wages or benefits
- One parent is unwilling to disclose income or negotiate in good faith
- You want a clear, independently calculated figure rather than an ongoing negotiation
When a Private Arrangement Works Better
- Both parents are amicable and communicate well about the children's needs
- You want to avoid CMS application and Collect and Pay fees entirely
- Circumstances change often and you want to adjust payments quickly by agreement
- You want to include costs the CMS formula does not capture, such as school trips, clubs or clothing
Worked Example
Private arrangement: Aisha and Daniel separate on good terms and agree Daniel will pay £350 a month directly to Aisha for their two children, reviewed informally every year and topped up for one-off costs like school shoes or a birthday. No fees are paid to anyone, and the figure changes by simple conversation whenever circumstances shift.
CMS calculation: When Ben stops paying the maintenance he had informally agreed with Chloe, Chloe applies to the CMS. The CMS calculates his liability from his gross income and their children's overnight stay pattern, and — because Ben continues to miss payments — moves Chloe onto the Collect and Pay service. Ben's payments are now deducted with a 20% collection charge added on top of his liability, while Chloe receives her share minus a 4% deduction, and the CMS has powers to pursue Ben directly through his employer if he falls behind again.
Frequently Asked Questions
What is the difference between the CMS and a private arrangement?
Does using the CMS cost anything?
Is a private arrangement legally enforceable?
Show 7 more questionsShow fewer questions
How does the CMS calculate the maintenance amount?
Can a private arrangement be for more or less than the CMS would calculate?
Can I switch from a private arrangement to the CMS later?
What happens if the paying parent under a CMS calculation stops paying?
Does either option affect Child Benefit or Universal Credit?
Which option is cheaper overall?
Can maintenance amounts be varied under either option?
Key Sources
Related Comparisons
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